All the information is stored on the ATS (Automated Ticketing System) main computer. This keeps track of all currently valid tickets and Resort IDs. Everything, including the finger scan algorithm, is tied in to the serial number on the ticket or card. All the cards on a reservation will have the same numbers except for the last few digits which will identify the specific card. This is why if you charge things to your room you can tell, on the folio, which card did the charging.