My thought was that it was either for a new member or a temporary card as if they had run out of preprinted cards. Several casinos have used temporary cards, the one that comes to my mind is the "Royal Subject" card used when Caesars Indiana first opened. Why Ballys had them I have no idea and never got around to asking. But I did mangae to harvest 4 or 5 of them.

I also have what may be two different Boomtown cards. I got a blank when I signed up and it is a slightly different color than the others I managed to harvest. The difference is so slight it won't show up on a scan so I will leave it to the experts to figure out if it is a variation or not.