Sometimes a question doesn't have a simple answer, and you wrote an explanation that is quite lengthy, using examples etc. And let's say that the answer is good enough to have gotten quite a few votes (let's say 10 is a good threshold).
Let's say a week later you realize that you could've taken an entirely different, and in your judgement, a much better approach. You'll explain it in a different way, with different examples, etc. Of course, since it is answering the same question, the eventual destination is the same, and there may be some overlap along the way, but the two paths are, at least in your judgement, still quite different in characteristics.
There are now two possibilities:
- Edit the first answer into the second answer. The first answer will be lost in the revision. The votes that were cast for the first answer are now, in some sense, misaddressed for the second answer.
- Write a new answer. It doesn't really matter that you have two answers now; it's allowed by the system, and presumably, it's allowed by the community
Which of the two is preferred?
For simplicity sake, let's say that the two answers aren't in disagreement with the other. There's nothing wrong with the first answer; it just choose to explain something one way, and now you've found another way to explain things that may be better.