If you want to take multiple bookings for the same staff and the same service at the same time, then, you can use "Capacity/Quantity Booking Feature".
Following are the instructions :
1. Login to your admin area.
2. Go to Settings --> Advance booking options--> Quantity Booking--> "Check " Allow clients to select the quantity for their appointment"
3. Also remember that, this setting will work for all services which has capacity more than 1 (Settings -->Services -->Clients allowed). And if it is activated on the client calendar, then all the available seats/quantity will be shown, and the clients can book the remaining of them.
Note : Quantity booking is a Premium feature part of PRO and above membership.