Oh yeah, you are definitely not alone. :) This is something that happens in all spaces. For example, I wrote a controversial blog post a while back and I had someone post four times in a row, using a different name each time, agreeing with him or herself. :) Fun!
I think that, in this case, it would be good to take action against the obvious ones and leave the rest. I think of it as a problem and I deal with it when it is obvious, but I try not to jump to any conclusions if I can help it. I sympathize with you, definitely.