George..in this case, just the Gold Coast as I mentioned. There certainly may be other strikes that have the .999 on both sides, and I do not collect from outside Nevada, but in this case it is only the Gold Coast and only the Slot Machine with the CT mint mark...that is what makes it unique. If the Royal Flush, Blackjack and Dice had the same design it would not be different, but none of these have the .999 on both sides, nor do they say "Collector's Series."