Cancellation of a reservation
The cancellation of a reservation is a withdrawal of reservation, which was followed by a payment transaction. It does not result in any loss of money resources.
You should keep in mind that double bookings (double booking) are controlled by the airlines, the seats can be automatically cancelled regardless of the tickets being issued or not for the respective seat. Therefore, having arranged several bookings for the same passenger and keeping the unnecessary reservations without cancelling them (whether in one agency or several ones), you are running the risk to stay without any ticket.