Multiple personalities seem to be a big deal for some posters. I really don't care because I'm not going to get emotionally involved with an anonymous person on a message board.
But I have seen others hurt very badly by it. In fact,
this post by Harper/Nikki/Roxxxanne makes me think that he/she is the cause of a great deal of hurt. I think this person posted as Nikki/Roxxxanne/eponine on Baltimoresun.com. As eponine he/she got a lot of posters to care about her and then posted as her sister saying that epo had committed suicide.
This blog shows a small part of what can happen when posters pretend to be what they are not.