I know Duplication is a bit of a contentious topic so I've looked around before asking this, but I can't find an answer. If I've missed it I'd appreciate being pointed in the right direction.

What does Closing a Question as a duplicate actually do? Particularly in the circumstance where different Questions lead to duplicate Answers. For example Hyperion Duplicate is closed as a Duplicate, but it obviously still exists on the site, a search for keywords in the Duplicate question still brings it back. I can still vote on duplicates (sorry if that's spammy).

If someone else wants to find the Hyperion books and only remembers the Dolphin planet, is there a time limit on how long they'll be able to find the answer via this duplicate, or will they generally have to wade further through search results than they might without the marking?

The only functional difference I've found is that I don't appear to be able to add an Answer, but obviously in the case linked above there would be no way to tell they were duplicates without Answers on both already, because there's no overlap in the Question text.

Looking at the tags in meta I might be confusing some properties of Close and Duplicate which appear to be separate processes.

  • 1
    Closing and duplicates are the same - duplicate is merely a close reason. Aside from that, another technical difference is that with duplicates, if you're not logged in, you'll be redirected to the duplicate target.
    – Mithical
    Commented Jun 6, 2018 at 9:36
  • @Mithrandir Only if there is no answer on the question..
    – user931
    Commented Jun 7, 2018 at 19:22

1 Answer 1


Duplication is a type of closure, but it's less punitive than other types.

We close questions as duplicates. The option to mark it as a duplicate is found under the list of vote-to-close options, for users with 3k+ rep who have the vote-to-close privilege (although if you're a lower-rep user flagging for closure, then "should be closed" and "duplicate" are two separate options).

But closure as a duplicate is considered less 'bad' than other types of closure. Both by the system (e.g. the bot which removes old closed questions doesn't touch duplicates) and by the community (we explicitly encourage people not to delete duplicate questions). Although this is more contentious, at least some of us also encourage people not to downvote questions just for being duplicates: my go-to maxim for this is that a duplicate of a good question is likely to be a good question itself. This is especially true for story-ID questions, where we have a policy to close as duplicate even when the questions themselves look unalike and contain different search terms, so the argument "OP of the dupe should have found the original question while researching their own" doesn't even apply.

Like all closed questions, duplicates still exist on the site (unless they're deleted, which is discouraged as said above). That means they can be found by searching, either within the site or using an external search engine, and they can be voted on. Don't worry about being "spammy": voting on dupe questions and their answers is absolutely fine. There's no time limit on a duplicate's existence on the site: they'll always be there, able to help future searchers and to act as a signpost to the original Q&A where the answer may be found. But, like all closed questions, they don't accept new answers.

  • For further reading, although they're old, they're still the basis of why things are the way they are: - Types of dupes: stackoverflow.blog/2009/04/29/handling-duplicate-questions - Linking dupes (explains how they can be good): stackoverflow.blog/2009/05/20/linking-duplicate-questions
    – Tony Meyer
    Commented Jun 6, 2018 at 10:24
  • 2
    Duplicate closures are a good thing and a well written duplicate should still deserve upvotes. I know I am just reiterating your point here but I think it's important this is highlighted because it's a "Close reason" and some people see that as bad.
    – TheLethalCarrot Mod
    Commented Jun 6, 2018 at 11:31
  • 1
    As Mith has commented above it is also worth pointing out that if you're a low rep or anonymous user/not logged in when browsing to a duplicate you will be redirected to the target.
    – TheLethalCarrot Mod
    Commented Jun 6, 2018 at 11:32
  • @TheLethalCarrot the point you and Mithrandir have raised there seems very strange. Especially when talking about non-identical questions for StoryIDs. The non-logged in user searches for "Dolphins not Sharks" finds a link with a title "Story set on an Ocean Planet" and a snippet that matches what they remember about dolphins, follows the link and is presented with a page talking about Pilgrims and Age Reversal, with not a single reference to Dolphins, in either the Question or Answer?
    – Jontia
    Commented Jun 6, 2018 at 13:25
  • @Jontia Odd for a case like that maybe but story id questions are a special case on this site. Remember this is a network and not just this site and features like this exist network wide. The reasoning behind the feature is that the better question/answer should be on the target so it's saving you the hassle of clicking through. Again remember that the network started from SO where this isn't really a problem.
    – TheLethalCarrot Mod
    Commented Jun 6, 2018 at 13:35
  • That makes sense, although it's about to walk me back to the question of whether it makes sense to mark StoryIds with very different questions leading to the same answer as duplicates, which my intro paragraph promised I wouldn't go.
    – Jontia
    Commented Jun 6, 2018 at 13:38
  • 1
    @Jontia As I said Story Ids are a special case and we currently have a policy to dupe them once both have been confirmed correct. If you can make a case against this policy you should post to meta (again) with your reasons against it and potential fixes (remove? only close similarly detailed ids? etc.)
    – TheLethalCarrot Mod
    Commented Jun 6, 2018 at 13:44

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