What to do with a good answer to a duplicate question after the closure?

Question

Recently someone asked about a Rogue sneak attacking on another's turn. I poked around, sure we'd answered it, found nothing, and answered it myself.

Later another user found the older duplicate question, flagged the newer question, and the newer question was properly closed through review.

Here's where it gets fun: the author of the accepted (and only upvoted) answer on the older question--and a diamond, to boot--mentioned that my new answer would be an improved analysis of the older question. (And what a mensch, to leave that comment.)

I see this sort of situation coming up occasionally as a quick and good answer beats the race with duplicate identification. So what's the best path forward? Some options I see:

• Leave it. All of it. Move on. The thing I dislike about this is that the duplicate question "has an answer" at all, which I think is sub-optimal.
• Delete the new question's answer, paste afresh on the old answer.
• Migrate the new answer to the old question. I think this makes best use of our voting system and collects all the answers to one question in the same place, both of which seem to be unrestricted "good"s. But I don't know if it's a thing.
• Smarter people come up with better ideas.

Answer 1

Optino #3, migrating, is totally possible and the most sensible option in this case. Mods have access to the merge tool, which—well, let me just paste the usage guidance beside its button:

Questions should be merged when they are 99% identical and it would be beneficial to have all the answers from multiple duplicate questions in one place. This deletes answers, moves them to the target question, and leaves the current question as a stub with a link to its merge target.

(This also merges all the comments on the page, apparently, which might be cause for tidying after the merge.)

So you can always use a custom flag to let the mods know that you think a question merger is a good idea.

The only caveat is that we're careful with merges, because unlike many operations on the site like duplicate closures and even deletes, merges can't be fully undone.

This brings in option #2: when a merge isn't obviously the right choice, or when flagged and the flag is declined because mods either plain disagree or maybe just don't agree enough to feel sure pulling the trigger, it's still within a user's purview to delete their own answer and post it elsewhere. That has the downside that votes don't migrate with it, but in this case that's a slight feature: the community gets a clean slate to judge whether it really is a answer, and how good, for the original duplicate question.

Answer 2

Another option I've seen done (not sure if it's been done on this SE site) is to reverse the direction of the duplicate link to point the older question to the newer one. I've seen this done in the specific instance where something in the newer question is identified as making it a significantly better target than the older one.