Don't know if double for more is common as I think it brings an extra advantage to the player but I am not sure maybe it is. I found a casino yesterday where they let me double for more, I did it once to see if it was really the case or if the dealer was incorrect. So I doubled a 2unit bet with a 3unit bet. The pay off was 7 units which seems even more abnormal but i think this was due to the fact that no one ever does double for more there and the guy next to me was telling the dealer how to pay me. Any advice on how to take maximum advantage of this Double for more without getting more heat and my bankroll isn't to big so more variance could be a problem.