Yea, I have Mr Niceguy and Mr Evil. Both are me. So in that sense I don't have an alter ego, "they" have each other.
But there have been times when a certain interest or activity or mood actually shaped me to the point I became someone "else".
Also if I have to do a boring task (mainly chores) I stand outside myself and instruct whoever is doing the tasks so I don't have to.
When I drink I just become chill. So I'm boring that way.