She accidentally double-booked both the hotel room and the restaurant for the same time, so now she has to cancel one reservation.

double-booked 是动词 double-book 的过去式，由 double（双倍的）和 book（预订）组成，字面意思是"双重预订"，指"同一时间段预订了两处不同的资源"，通常会导致冲突需要取消其中一个预订。