The only way you would run into a problem is if you tried to use it by more than 1 person in a day. Say, your Sis uses it in the morning and your brother wanted to use it at night. When they see it's already used that day, then can ask to see the handstamp the first person gets when exiting the park. The handstamps are to prevent the passes from being handed off in the same day. On different days, they have no way to know. The room keys are always in the name of the person whose name is on the reservation. So if you had a 12 person DVC grand villa, all 12 room keys would have the same name, not individual names.