Candidates can schedule interview for the time slot that has been already booked

Summary: For Job Requisition using shared Interview schedule candidates can schedule interview for already booked time slot

We have created and added shared candidate interview schedules to the job requisition, and sent an invite to candidate to scedule an interview. Candidate can see and select the same time slot that is previously reserved for an interview by some other candidate. 

We had already enabled the profile option to prevent multiple interviews from being scheduled for the same interviewer on the same date and time. If we use a standard interview schedule rather than a shared interview schedule on job requisition, candidates cannot book the same time and date for multiple interviews.