stopping multiple user from booking same time slot together

Does dhtmlx scheduler prevent multiple users from selecting same time slot if they select a tmie interval at same instant .

Normally it doesn’t prevent anything.
But you can attach custom logic to server side saving logic, which can block data saving if time slot is already occupied by another user

Also, there is a client side collision preventing extension, which will block any new event for already occupied time slot. … collisions

Will it prevent collision when multiple user select a particular time slot to save the event at the same instant?

Nope, it only block new event creation if info about possible conflicting event was already known.
If we are talking about instant collisions - they can be blocked only at server side code.

kk thanx.