Let me give you a complete overview of how Room Types work in QloApps.
At the backend:
We create Room Types by clicking on Catalog Tab--> Manage Room Type--> Add New Product.
While creating the room type, on the configuration page we enter the maximum number of adults and children that can be accommodated in that room type and then we add rooms to this room type. The admin can add any number of rooms to this room type.
Now at the front end when a guest tries to make a booking, he books the room, not the room type. So the quantity available for the booking is the number of rooms which admin has added in that particular room type.
So multiple rooms can be booked in a date range.
If you want to book one room at a time then just select the date range and make the booking and if you want to book a room in a different range then select the date range again and make the booking.