Scheduling conflict pop-up for duplicate bookings

When an employee is double-booked, no pop-up currently appears to indicate that there is a conflict because the employee has been scheduled twice at the same time. The request is for a pop-up to appear in this situation, indicating that there is a conflict for this specific employee. The pop-up would then allow you to choose whether to proceed with the action or cancel it.

This protects the scheduler from making mistakes.