0 present participle of double-book --
1 to promise the same room, seat, ticket, etc. to more than one person or group: --
The room was double-booked so they had to give us a different one.
The union will often enforce a basic code of conduct amongst its members to ensure smooth operation of the hiring hall (to prevent members from double-booking, for example).
Software is often differentiated by whether it allows double-booking, or whether it uses a scheduling or a booking model.
Hospitals are downsizing their capacity to the minimum, rather like airlines double-booking many of their seats.