I'm going to assume this is a serious comment because I am familiar with the concept of people with multiple identities know a couple. For such people, the question may not make sense for the reason you state. However the question is not so much about identity as it is about ownership and responsibility for a persona and their utterances. Many of us have different personae; I am sure my family, cow-orkers and friends interact with different aspects of me. In each case, however, I own that persona and am that person. Perfectly "normal" stuff. The question really is; to what extent, on the Internet, are we willing to disassociate our identities from our personae? Especially when doing so allows us to say things that we would not in a meat space public forum, for various reasons.