It frequently happens across all SE sites that duplicate questions garner a few answers before they get closed. Sure there should be a policy about not answering dupes, but only the high rep users are likely to know when something is heading towards closure.
- Some users don't realize the question is a duplicate and make their best effort to answer.
- Some are looking for some quick free rep.
- Sometimes recognizing duplicates and closing them can take a lot of time.
But never-mind the reason. The fact is sometimes valuable answers show up on questions before they get closed as dupes.
These answers are frustrating for a couple of reasons. Often the answers to the original question are more mature, but because answers show on the duplicate they often get looked at and even voted on. The rep trolls get fed and answers aren't fairly voted on against each other, only against a subset still showing on the dupe.
Sometimes the reverse happens. A better answer will turn up on the new question that isn't in the old question. This happened to me today when I wrote up a thorough answer to a new question, then later found that I'd answered the same question some months back with a two liner. I voted to close the question, leaving MY answer as the one locked on the closed question. I opted to delete it and edit my old answer, but gave up the rep from my better answer before the question got closed. This made me realize the toolset could be improved.
...that when a question is closed as a duplicate, the default behavior should be the assist in migrating the answers to the new question to the old one. If the question is truly a duplicate, answers should be mergeable. There is value in leaving a duplicate question to be found by future users that search the specific wording, but there does not seem to be value in leaving answers hanging around on closed question that should be found under the duplicates.
- Answers merged from recently closed questions will be at a time disadvantage compared to old ones, but this is fair. If they are duplicate answers they will float to the bottom. If they are better they will get voted up.
- Rep trolls will go that much hungrier.
- Better answers won't be in the awkward position of being locked.
Additionally answer posters could be prompted for how to handle their own answers to anything that is closed as duplicate. These prompts could include:
- Migrate to original question?
- Edit and migrate?
- Convert to comment?
In the end, questions closed as duplicates should not have answers floating around on them. Right now they do, all over all the sites. I realize there is some kind of merge function available to moderators, but the majority of questions aren't handled that way they are closed by votes and any answers posted before the close generally stay put.