double-book
verb [ I or T ]
ukusto sell the same room, seat, or share to more than one person:
A customer complained that they had double-booked his room.
21.4 million shares were booked as having been bought, but later were found to have been double-booked.
to agree to be at two meetings or events that happen at the same time:
Make sure your diary is handy so you don't double-book.