Only 1 Reservation per Slot

Hi,
After creating a slot, for example, with a limit of 20 reservations, the same person can click on that slot several times and make the reservation.

* It shouldn’t be possible!

One thing is the client to be able to book X slots on different days or at different times of the day or week. Another thing is the client to be able to click on the same slot several times and make a reservation.

Is it possible to prevent a person from clicking more than once in the same slot but allowing him to click in other different slots, on the same day or another day of the week?

I am using the plugin on a Gym website and I want customers to be able to make multiple bookings for the entire week, but only select the same slot only once (on the same day).

The page I need help with: [log in to see the link]