Not sure about having two faces but I think I have two brains. One where I wander in my mind thinking of anything possible, analyzing stuff and the other where I actually talk with people. Usually if I'm wandering inside my brain I can still participate in a conversation somewhat but probably wont be listening much, that's most likely when I come out as timid and not my usual extroverted self. I do that when I am not interested in what is going on around me, as in boring or I am preoccupied with something else that is bugging me more.

Not sure if that bipolar, I don't consider it as a disorder or an illness.