Recently I encountered the scenario in which the same person posted more than one answer on a question. I wondered and checked, and it's indeed possible, with a single warning showing up. But I was curious whether there are any restrictions on such answers, or implications of answering like that. Moreover, what is the reason for allowing that in the first place, since the user can edit the answer?
It is something you should rarely do, but there are a few valid use cases. I'm not convinced it is actually necessary on the main sites, but it is rather useful on metas. In most cases it is a better idea to keep everything in one answer, even if you have multiple different approaches or solutions.
Something you should never do is to use this ability to shed downvotes or circumvent deletion of your post by just reposting the same answer.
Allowing users to provide more than one answer is advantageous because it means that if there are two potentially distinct solutions, that have nothing to do with each other they can be voted on, edited, deleted ect individually rather than affecting what would have been one answer.
This generally happens when one user is providing an answer for both sides of 'argument'.