On all SE sites users can post multiple answers to the same question. There is a warning dialog if you do that, reminding you that you can also edit your existing answer.
The only valid reasons for adding multiple answers I can think of are
- They are single-item answers to recommendation questions, which are discourage anyway
- It's on meta, and they are about different approaches. Separating them allows the community to properly vote on them.
Invalid uses of that feature that I have encountered are self-deletion and reposting to get rid of downvotes as well as reposting moderator-deleted answers.
If you want to provide two fundamentally different approaches to the same question on the main site, I think a comprehensive answer discussing both is better than separating the answers. If you provide multiple approaches, an important part of the answer should be detailing the advantages and disadvantages of them. This can be done better in a single post than in multiple ones, in my opinion.
Multiple answers also don't play nice with the reptutation system, they are often perceived by the community as a cheap reputation-grab. The availability of this feature can mislead users into using it inappropriately, as there are only few cases where it is actually useful.
So, does it make sense to allow multiple answers on the main site, or should this feature be disabled? To be clear, I want to keep it on the meta sites, as it is useful there.