Boxes are delivered containing 500 cards. A box is opened, a stack is removed and placed at each of the Registration Desk workstations. Guests check-in and keys are issued from the top of the stack, in the quantity needed for the number of guests. By happenstance, my brother-in-law was in town and was staying at the hotel. Based on past years for this event, I suspected that there might be 10 different keys, so I asked and the clerk was kind enough to grab a very short stack. Turned out to be 10 different, with 5 duplicates. I suspect that they are loaded into the boxes of 500, in a sequence of 10 different, for 50 sets per box.