Answering duplicates often happens in good faith. Even active Meta users with a crapload of dupe-fighting feature requests often rush to the "answer" button ("hey, I can write a cool answer to that!") before pausing for a second to think whether this might be a dupe. It's a natural impulse, and not wrong as such. After all, it's the reason why SO exists, and has good answers.

However, as long as answering duplicates is rewarded, and finding a good original to close it with is not, we have an ever growing problem: a flood of mediocrely answered dupes that, even if you stop worrying and start loving dupes, are worthless, because they have no connection to a high-quality original. A Googler happening upon an unclosed dupe hits a cul de sac: there is no sign pointing to the much better original question whose answers have been reviewed, critiqued, and modified many times over; they are stuck with the mediocre content, and may end up thinking that is the best answer that exist, on SO anyway. This is contrary to the idea of Stack Overflow as a high-quality archive of canonical answers.

Not awarding reputation to dupe answers has been discussed, and it's been turned down, IIRC mainly on the grounds of not pissing off answerers, which I guess is a valid point.

How about combining a softer CW approach with an invitation to good answers to be moved to the original question instead?

  • If a question gets closed as a duplicate, make the question and all its answers Community Wiki automatically, from that moment on (but not retroactively).

  • Allow authors of any answers above a certain vote threshold (+3? +5?) on the duplicate to migrate their answer to the original. Either invite them to re-post their answer on the original; however this would create duplication in answers, as the author would be unwilling to delete their answer in the dupe because they'd lose all the previously gained rep. That would have to be addressed somehow, or the feature isn't going to be used much. Or, create a migration tool that merges answers on a per-answer basis, triggered by the answer author, showing them a message like this:

    > # Thanks for your answer.
    > This question has been closed as a duplicate of an existing question. It looks like you wrote a good answer - we invite you to migrate it to the original question, "concatenating a string"! **Click here** to start migration. Please after the migration, check your answer's wording so it makes sense even in response to the "new" question it then answers.

    (an answer migration tool operated by the author instead of a mod is obviously an UI and UX challenge that would have to be thought about in more depth than this, but you get the basic idea.)

What good I think this would do:

  • Further activity on the duplicate would be gently discouraged, and attention be turned towards the original question.

  • Relatively new users with high-quality contributions would be made aware of the existence of duplicates, and be educated in how SO values building an archive of canonical questions.

  • Authors of good answers have a reason to re-post on the original: it's the only way they can keep gaining reputation.

  • The original would get new attention, and possibly a new great answer it didn't have before.

  • You would stop gaining reputation on the dupe, but the overall experience would be a positive one - you get to keep all the points made prior to the CW, plus you get invited to add your answer to the original question.

How about it?

  • you get to keep all the points made prior to the CW, plus you get invited to add your answer to the original question -- that conflicts with encouraging deletion of the original answer after copying it? (I guess reputation would be preserved if a moderator merges two questions?)
    – Arjan
    Mar 11, 2012 at 22:10
  • @Arjan good point - preserving the rep would speak in favour of some auto-merge tool (triggered by the answer author, not the mod) for good answers. I think I'll update the suggestion with that
    – Pekka
    Mar 11, 2012 at 22:12
  • 2
    I don't particularly agree here. Dupes rarely get TONS of votes after closing and good-faith, high quality answers deserve rep, IMO even if they were given to a "dupe" exactly for the reason you mention here; the dupe's answers may actually be better.
    – Ben Brocka
    Mar 11, 2012 at 22:19
  • 5
    @Ben I agree. That's exactly why I suggest encouraging the migration of good answers into the original, where they can continue to earn rep. I don't mind the dupes hanging around as pointers for incoming Googlers, but the actual answering activity needs to be concentrated in one, canonical question instead of scattered across the network (in wildly varying quality).
    – Pekka
    Mar 11, 2012 at 22:20
  • 1
    Related on MSU: How can we take care of our old duplicates?
    – slhck
    Mar 11, 2012 at 22:27
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    How many answers would eventually migrate to the first "how to concatenate a string in [language]?" question? Is there a point to limiting or discouraging answer migration if the destination already has plenty?
    – sarnold
    Mar 12, 2012 at 1:17
  • @sarnold good question. My first thought is there's no point in imposing limits - the new answer that comes in could be exceedingly brilliant, or information that isn't on the target page yet. So the simplest way would be choosing the minimum vote limit wisely. I could however also see a more complex algorithm though that takes the target question's "population", its age, last activity, locked status etc. into account, and displays the invitation based on those factors
    – Pekka
    Mar 12, 2012 at 1:21
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    I don't think vote count is a good indicator, unless you set it really high. Depending on the dupe, the top answer may very well be an RTFM with 9 upvotes. People vote up what they know, the simple answers tend to get a lot of votes. There's often no point in compiling them into the supposed canonical post. I think this is wishful thinking at best, failure in practice. +1 anyways because I agree with the spirit of the request.
    – user159834
    Mar 12, 2012 at 9:39
  • @Mad hmm. I have not seen that (an RTFM being upvoted this badly) happening for a long, long time. I wouldn't be against raising the vote threshold but seeing as the OP can also just manually answer the original, I don't think this will lead to a lot of damage.
    – Pekka
    Mar 12, 2012 at 9:59
  • what if a closed question is better than the one that remains opened?
    – gnat
    Aug 20, 2012 at 20:09
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    @gnat: Flag for the situation to be reversed, or make a post on Meta calling for close and reopen votes?
    – jscs
    Aug 20, 2012 at 20:20
  • 1
    @Pekka: I wish I could cast new upvotes for your suggestions every time they pop onto the front page. Keep thinking, man! You're doing great!
    – jscs
    Aug 20, 2012 at 20:20
  • @JoshCaswell I see. How would such a dupe-tango interplay with suggested auto-CW feature? would the swap also toggle CW status somehow? - or would it be kept as is - somehow "penalizing" the better question?
    – gnat
    Aug 20, 2012 at 20:26
  • 1
    @gnat: That's what I imagined, yes. I can't see this proposal working any other way than to have the CW status change as soon as dupe status is established. That does open up the potential for an answer to be migrated (or offered to be migrated) multiple times, I suppose. That's a wrinkle, to be sure.
    – jscs
    Aug 20, 2012 at 20:33
  • 1
    Too complicated. Just close and delete them. Tough luck for those who answered it before searching for a fitting dupe.
    – Gordon
    Nov 25, 2012 at 17:07

2 Answers 2


You start by describing the cul-de-sac problem where questions don't get closed as dups, and then propose a solution that involves identifying a dup. I"m not sure how that would work.

If a question isn't marked as a dup, there's nothing to move answers to. If a question is marked as a dup, then moderators already have the ability to merge the answers, so what may be needed is broader awareness of that. (Note, though, that answers sometimes require rework, because dups are usually not exact despite the label.)

However, one change that would help without requiring moderator action would be for the dup-pointers to be bi-directional. When a question is closed as a dup, it already gets a link to the question it's a dup of (which is good). The target of a dup could also have (at the bottom) links to questions that were closed as dups of it. In addition to leading to related material, it might help raise general "check for dups" awareness, much like Bugzilla's "frequently-filed" bugs report.

  • 2
    This is actually a combined suggestion - CW'ing answers to duplicates, and providing a migration tool. The former is to encourage a culture of looking for dupes instead of answering a question straight away, addressing the cul-de-sac problem. I'm aware of merging, but it is extremely rarely used, and doesn't (AFAIK) allow the "selective" merging of good answers only. A migration tool that puts users in control would make sure the answer is reworked, and only the good stuff gets migrated
    – Pekka
    Aug 27, 2012 at 21:26

The current state as I understand it, is that a question is marked "Closed as an exact duplicate" at the bottom, and links to possible duplicates are edited in to the top of the question (as seen in https://meta.stackexchange.com/questions/125511/mark-duplicate-questions-with-duplicate-instead-of-closed).

In my opinion, instead of linking to the original question, it would be better to simply display it (and it's answers) below the duplicate question.

You would then get a page structure like this:

[duplicate question]

"This question has been marked as a duplicate of a pre-existing question on stackoverflow, below you can see both the original question and answers to this question which should also be relevant to the question above"

[original question]


This page would still have an answer button: any answers would simply get added to the original question (and would of course also come up under the duplicate question). Some care would have to be taken in ensuring that people knew which question they were answering, and didn't refer to specific parts of the duplicate question, but considering that the duplicate system is only supposed to be used for exact duplicates, this shouldn't be too much of an issue. In fact, as a bonus, it might encourage people to more thoroughly consider whether or not the question really is a duplicate (if it can't be answered with the same answer, then clearly it is not).

Finally, some consideration would have to be given to when duplicates should appear in search results (you don't want 5 links to the same question coming up). I think perhaps it would therefore be best to distinguish between two types of duplicates:

  1. Those where the (correct) answer to the question is substantively the same, but it is worded differently (which should be displayed as above, and shouldn't be a problem for search results, as they are worded differently)

  2. Those where the answer to the question is the same, and it is worded the same or very similarly (which should probably be simply merged, or even deleted)

This solution would have to work in tandem with Pekka's migration tool suggestion, although it might be possible to automatically migrate answers with a certain amount of reputation. It would mitigate the problem of rewarding duplicate answers, as all of the answers would be in the same place, they would just be viewable from multiple different places.

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