Preferably, when closing a duplicate, this happens before any answers have been given to the dupe-to-be. However, it can happen that only after editing of the question and multiple answers, it turns out that it's actually a duplicate.

Should we then always vote to close the newer question as a duplicate, or should we try to keep the better question (or the question with the better answers) and vote to close the other question, even if that is the older one?

An example: we have the questions "What's the significance of this passage from “The Goblet of Fire”?" and "Why was Dumbledore worried by the cut in Harry's arm?".
The latter was asked about two months after the former. And while the OP of the latter insisted that his question was specifically about the cut itself, rather than the fact that Voldemort used Harry's blood, the accepted answers are very much the same, which makes them duplicates.

But which one should we close?

Both have good answers, but I think the answer in the second question is more complete than the answer to the first one, so I would prefer vote to close the older question as a duplicate of the newer one.

On other stacks, such as Math.SE, this isn't uncommon practise. Perhaps we should adopt it too.

Or are there other options, such as merging? (I've only read about it, I've never seen it happen; it seems uncommon).

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    Merging duplicates is a moderator-only tool. Or at least, it was when the technique was introduced: – alexwlchan Jun 19 '14 at 14:14
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    @alexwlchan It still is, and it's a very dangerous and rarely-useful tool. It only works if the questions are not only semantically duplicate but also worded in very similar ways. And it can't be undone, so you have to be really really sure before using it. – user56 Jun 21 '14 at 8:12
  • @Gilles: I guessed as much. I’ve very rarely read about the feature, and never seen an instance where it was used. – alexwlchan Jun 21 '14 at 8:13
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    "the accepted answers are very much the same, which makes them duplicates." How so? I would have thought that questions don't become dupes because their answers are the same. If two questions qualify as distinctly different, then regardless of whether the same answer applies, the fact remains that the two questions are asking distinctly different things. By reductio ad absurdum: would you mark as dupes the questions "Why did my boyfriend dump me?" and "Why is my boss acting this way?" if the legitimate best answer was "Because people are assholes"? – Lou Jun 22 '14 at 23:52
  • @LeoKing, yes, on Stack Exchange, I would. :) The text reads "this question already has an answer here: (...)" (emphasis mine) which means we're really looking at answers, not at questions per se. Of course, your example really is reduced ad absurdum, and the answers have to be the same including context of the question. More common, legitimate cases are questions that are closed as duplicates before they're answered and narrow questions that are answered by a broad answer. But also (rare) cases like this, where questions are only discovered to be duplicates after answering. – SQB Jun 23 '14 at 6:01
  • When a high rep user asks a dupe question, close the original one as dupe. – Awal Garg Jul 1 '14 at 10:12
  • The closing process is about defective questions. Answers have nothing to do with it. (Answers are addressed by up and down votes.) See my answer, below, and I'd ask the you reconsider your accepted answer. – Wayne Jun 17 '17 at 21:18
  • @Wayne Even if SQB were to accept your heavily downvoted answer, site policy would still be decided by community consensus, i.e. by the most upvoted answer(s). (For this reason, I generally advise people to accept the highest-voted answer on meta policy discussions, so as to keep things clear.) – Rand al'Thor Jun 18 '17 at 11:40
up vote 15 down vote accepted

Remember that the main point of closing-as-duplicates is to help people find a single source of answers when searching.

As such, the preference should be:

  1. If one question covers a subset of the other, the more specific version should be closed as a duplicate of the broader one.

  2. If they are essentially the same, the one with the better answers should be left open, and the other closed as a duplicate. This usually, but not always, results in the older version being left open.

If the wording of the closed question is better than the one being left open, then the one being left open should be edited to improve it (so long as this can be done without changing the meaning).

If the question to be closed under the above guidelines has good answers, then the questions should be flagged for merging.

  • Totally disagree with this answer. The purpose of closing duplicates is that people are able to find a single source for an answer because people don't lazily open up questions that have already been answered. Hence the name "duplicate". Rewarding question sniping by closing an older question that has reasonable answers is the opposite of a solution, since it actively rewards not searching for previous answers and throws away hard effort by those who answered the older question. (Unless the older question essentially had no answers.) – Wayne Jun 15 '17 at 22:02
  • @Wayne in neither scenario I described does anyone get rewarded for lazily sniping an existing question, nor does the effort of people who put effort into good answers get "thrown away". – Beofett Jun 16 '17 at 0:54
  • It is true, that closing the question does nothing wrong or good to the answerers or askers of neither of the questions. It only marks the question as the duplicate, that is all. – TGar Jun 16 '17 at 10:35
  • @TGar: Closing a question may or may not do anything to the accumulated votes. I don't know the mechanisms so will have to trust that you are right. However a closed question will not garner further votes, and a newer question that is a duplicate of an older question will siphon votes from the older question and its answers. Votes don't matter that much, so the real damage is that people ignore closed votes. "Duplicate" has connotations and people will tend not to read them -- that's the whole point of this exercise -- so you do rob answerers of attention to their hard work. – Wayne Jun 16 '17 at 12:15
  • @Beofett: A closed answer is first of all downgraded in readers eyes. A closed answer will not receive up votes, nor will it receive views. A newer answer may hit "Hot Question" lists, etc, while an older question will not. Even if the two questions are merged, original answers which are good will have had up votes siphoned off by the newer questions answers. And merging is the best-case scenario, which in my experience doesn't happen very often: people usually vote to close as duplicate and that's that. – Wayne Jun 16 '17 at 12:22
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    @Wayne closed questions, and their answers, can, and do, receive votes after being closed. Closing does not change accumulated votes, nor does it prevent new votes. That entire premise is faulty. And an old question will never hit the HNQ list, regardless of whether it is open. Merging requires a moderator, so if you think duplicates should be merged, flag them. – Beofett Jun 16 '17 at 13:34
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    @Beofett: I am mistaken, then, in terms of the physical mechanism. Still, being "closed" will discourages votes, even though they can be cast. And the fact that a newer answer can cause an older answer to be closed does encourage sniping and discourages people from searching for existing questions that answer their curiosity instead of immediately posting whatever came into their mind. "Duplication", in my mind is to discourage new substantially-similar questions in the same way as "unclear what you're asking" is to discourage poorly-thought-out questions. It more directly achieves your aims. – Wayne Jun 16 '17 at 13:51

No. In general, choose the better one to keep open, as long as it is significantly better.

There are multiple things and situations to keep in mind:

  • If the newer question has yet to gain answers, don't VTC the older one. It's weird, since that one has the answers.
  • One thing you haven't touched on (which has happened a couple times on SciFi.SE) is that the newer question is broader, but not enough to get closed as "Too Broad".
    • If it can get edited down to no longer be a duplicate, that's the best route.
    • If that's not possible, then I think it's alright to VTC the older one as a duplicate of the newer one.
      • I vaguely remember a Harry Potter one being like this, due to the nature of the question - the older one was about two characters, while the newer was a general case that applied to those two characters.
  • If the newer question is significantly better and already has some good answers, then I think VTCing the older question is okay. Due to the subjective nature of "better", there is likely to be friction here, so if there's a fight between closers and openers, bringing up that specific question on Meta is a good idea.
    • Because this is the least common course of action, it's also a good idea to leave a comment on the newer question as to why you're closing the older one as a duplicate of the newer one

For the two questions linked in the question, this is one of those borderline cases that doesn't really fall into any of the buckets in the previous bullets. It's unfortunate that user8252 is no longer on this site, but the new one doesn't to me seem to be significantly better - so the normal course is to close the newer one.

Additionally, if one question is marked duplicate of another, they both have answers, and are deemed to be identical enough, they can get merged into one question by mods or supermods (I'm not sure who exactly this power is given to). This is extremely rare, though, since the questions closed as duplicate are used as signposts towards the "original" still-open question - and doing the merge loses that signpost.

  • Note that merging does not delete the duplicate version. It simply marks it as a duplicate and migrates comments and answers to the "master" question, so mergers still assist in helping people find the signposts. – Beofett Jun 20 '14 at 13:09
  • "If the newer question has yet to gain answers, don't VTC the older one. It's weird, since that one has the answers." That shouldn't even be possible any more, as far as I'm aware. The actual close vote should be blocked, though I believe you can still manually enter the URL for an unanswered question in the dialog. – Anthony Grist Jun 20 '14 at 19:24

The accepted answer is incorrect:

enter image description here

This is a screen capture from another Stack Exchange site, but as far as I can tell they all operate on the same principles. Note that "duplicate of" indicates that the question being closed is the second one. It follows the obvious meaning of "duplicate": that an answer has already come before.

Also note that all reasons for Closing are because of a problem with there Question. Answers have nothing to do with a Close vote. In the case of a duplicate the problem is that the questioner did not search adequately for the question already being asked. And this is the one reason for closure that has an objective measure: which came first. All others are to some extent subjective, but not duplication.

Yes, there is a subjective aspect to "duplicate", which is if the two questions are pretty much the same or not. None the less, if a new question is asked in error (is a duplicate) but is not noticed for some time and perhaps even gets good answers, the solution is to merge the answers into the original.

The accepted answer is a novel theory, but totally goes against this. It closes questions based on answers and retroactively considers an older answer to be a "duplicate" of a newer answer.

The accepted answer also contradicts the whole meaning of closing a question. Questions are closed because of defects that the questioner is unwilling (or unable) to remedy. They are not closed because of answers or because of questions that might be posted years later.

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    Regardless of what other sites do, a long standing (but often controversial) policy here has been that answers define duplicates as well. If you believe that they shouldn't, I get you, but that's a different battle. – phantom42 Jun 18 '17 at 1:59
  • Yep, I believe it shouldn't. It simply encourages lazy question asking and question sniping rather than quality. May as well take a question that has a confused answer and close the question as "unclear'. – Wayne Jun 18 '17 at 2:50
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    @phantom42 The meta post you linked is from 2012; this is the most recent consensus on answers defining duplicates. However, I don't understand what this issue has to do with what's under discussion here, the dependence of duplication on age. This answer seems to be talking about two separate issues. – Rand al'Thor Jun 18 '17 at 11:37
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    My point is that it is a long standing policy dating back 5 years. – phantom42 Jun 18 '17 at 14:15
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    @phantom42: Long-standing and inconsistent with all other closure reasons and most if not all other Stack Exchange sites. And an encouragement to questioners to not look for existing answers, which leads to exactly the opposite result of that desired: multiple questions and loss of answers. (Duplicate messages do not point in both directions, so the "duplicate" is essentially lost in the mists of time.) – Wayne Jun 18 '17 at 22:59
  • @Randal'Thor: The linked-to post is using the same quirky reasoning that in one case out of the several for closing a question, the question's answers can cause the question to be closed. That is what the accepted answer in this thread recommends, on steroids: the answers to one question can cause a separate question to be closed. Leaves me little incentive to ask questions or answer them in this site. – Wayne Jun 18 '17 at 23:04
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    Again, if you don't agree with the policy of answer-based-dupes, take that fight there. This is a separate issue. – phantom42 Jun 19 '17 at 11:12

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