Yes. I personally do this already.
Obviously, it is preferable that we keep all the answers existing to the same question. But we are working within constraints and keeping the best content is the easiest solution available.
Although, copying and pasting your answer content into the old question isn’t very hard.
This would be nice, but it's not pleasant chasing people up about re-posting answers constantly. No guarantees they ever will, which makes it an inconsistent solution.
I don't think that should be made the "protocol" but other people may disagree.
I feel like this could very easily turn into people trying to find old and outdated questions just so they can ask them again themselves in a cheap attempt to get points.
I don't think people would actually do this, but if they do and that becomes clear, then we will make them stop. I think it's a silly way to get points, because you already know the thread is likely to be closed.
add a feature for merging questions or moving answers
This would be nice. Moving answers especially would be great.