It would be nice if Stack Overflow had a feature to join multiple answers into a single answer
Especially in red hot questions like
c# vs Java where multiple answers when joined together would make more sense.
If you find a situation where there are a number of roughly equivalent answers, some of which supply useful details that others lack, then the best thing to do may be to edit the first (time-stamped) answer of the equivalent set to add in those details. Then vote up the one you enhanced.
In my experience, though, if multiple answers to a technical question differ, there's usually one that's clearly better than the others, and the other ones are pale imitations (sometimes they really are imitations.) Then you can just vote those down.
This doesn't hold on Meta; discussion questions can have multiple "best" answers.