Say that we have the following hypothetical question and answer on the site:
Q: What race is Gandalf?
A: In Letter 123, Tolkien wrote: "Gandalf and Saruman are Maiar."
A year later, another user asks this question:
Q: What race is Saruman?
Is this second question a duplicate of the first because the other question has the answer in the quote from Tolkien, and the same quote could be used in the new one?
I ask because I've seen a number of questions closed as duplicates that basically boil down to this situation. What usually follows is a string of comments where people argue about if it's really a duplicate (often including sentiments like "How was I supposed to know to look at that question?").
I am aware that there are other options like editing the first to be a canonical question, but since that's not always practical or desirable, I want to focus on whether or not these two would be duplicates in their current form.
This might have been addressed in previous meta topics, but since most of them are really "should this specific question have been closed as a duplicate?", I'm hoping to better understand our general duplicate policy without reference to any real question.