Preventing a manual double booking

I am using Bookings through MS Teams to manage dorm rooms scheduling. Essentially, each of the dorm rooms have a resource email account that are then entered as staff into Bookings. I then create a "room reservation" to annotate the customers stay. The resource accounts are setup through our website and not through our MS organization. This forces them to be guest accounts which greys out the box for Office Calendar availability.

Although some of the reservation requests will be placed by the customer, most of the time I will be creating a manual service. However, I cannot figure out how to prevent a double booking of a room (i.e. staff member). Essentially, I am looking for the app to deny a booking that is already on the calendar.