How does RecTimes prevent duplicate bookings?

When you add a booking from the calendar, or when an booking is made online by a customer you don't need to worry about duplicate bookings because the calendar is updated in real time. 

If a customer starts the booking process and does not finish before Admin or another customer makes a booking for that same time slot then the customer will be notified that the time slot is no longer available for booking and the customer can then choose another booking time.