So as not to confuse things, only one reply can be marked as an actual "answer." However, it IS possible to "like" other replies, which essentially marks those replies as "additional answers."

 

Look at something like Quora, where "answers" are essentially designated by a large number of Upvotes. In SmarterTrack, liking replies is the same thing and a large number of likes for a reply will designate it as an "answer" even if it's not actually marked as THE answer.