i think its a good idea = because i know some people don't even bother to look at a question if it has a few answers, as they assume its been sorted - that's why sometimes its irritating when people make jokes or chat on serious posts - or say stuff like 'oh yes, i have that problem too', or 'i've always wondered this' or something useless
some people also assume their answer is correct and therefore it should end the post - and get a bit antsy if someone else adds a similar answer.
personally i would rather 10 people answered with a similar answer - so i can be sure its correct and the best one, rather than just one answer, as people can be wrong.