Overlapping times for staff

[evandp01]

I am having a hard time finding anything that specifically addresses my situation.

I have staff that work with clients. Typical shifts will be on a single date, but occasionally, hours will cross midnight.

Service codes can vary, and staff may work 12pm-5pm with one service and 5pm-8pm with a different service or client.

I input staff, client, date, Time In, Time Out, along with other variables that are relevant to their pay.

I am trying to monitor 3 things.

When staff time is entered twice (this would be duplicate staff, client, date, and time)

When staff overlaps their time on the same date (2 shift times overlap, regardless of client listed)

When client times overlap on the same date (2 shift times overlap, regardless of staff)

This does not have to be accomplished in a single column, I can measure each of these seperately. The first one is easy enough, it is the second two I am having a problem with.

Shift times can end and begin at the same time, e.g. end time of 1:30pm and start of another shift time of 1:30pm. This is where I have had a problem with it not giving the result of an "overlap".

I hope I am explaining this well enough!

Thanks for anyone's help!