I'm not sure but I remember reading a similar discussion back then as the player tried to point out there was one casino that had a slightly higher payout compared to another casino even though the game is the same.

I think one of the slot providers that lets you do this is Booming or Betsoft, not sure if it's both of them but i'm sure that the name of the provider is starting with the letter "B" since these are the providers that most casinos have back then.