Re:Why both games under the same entry
I've wondered about that too, Bruno.
Actually BGG used to have both games on different entries but they were merged in october 2003. You can still see the ratings SuperGang used to have in the Articles section posted as "More ratings". I never officially asked about the merged entries because I've never played Gangsters, so to me they COULD have been the same or very similar games. (Although I can see some differences from the Gangsters session reports I've seen on the web.)
But if you have played the two games and can justify separate entries, I think you can bring this up to the BGG administrators Aldie or Derk.
In any case, I certainly would like to know who decided to merge both games and why both games are in the same entry. Personnally, I think this situation robs some the limelight SuperGang deserves.