Paul Bogart's birth name is Paul Bogoff.
Leslie Bogart's birth name is Leslie Howard Bogart.
Nicholas Bogart's birth name is Nicholas Charles Bogart.
Neil Bogart's birth name is Neil Bogatz.
Paul Le Paul's birth name is Paul Braden.
According to the imdb (Internet Movie DataBase) entry for the film, the name of Bogart's character is Harry "Steve" Morgan. I guess Steve is some sort of nickname, but, since I've never actually seen this movie, I don't know where it comes from.See the Related Link below for the imdb entry for To Have and Have Not.
Paul Zenon's birth name is Paul Collins.
Paul Alexandro's birth name is Paul Jaure.
Paul Mantee's birth name is Marianetti, Paul.
Paul Landres's birth name is Paul Katz.
Paul Shaffer's birth name is Paul A. Shaffer.
Paul Rotha's birth name is Thompson, Paul.
Paul Knepler's birth name is Paul Knpler.