Did something like this for overlapping machinery downtime.

Suggest you:

- put the data rows in chronological order by one time or the other (let's say Start Time)

- formula in Column D checks IF C1 falls between B2 and C2 and if so, returns 1 (or any value you want)

- drag that formula down the range

- range E2 could contain the Count formula for D as far down as you want to go (or sum if using 1's).

That would give you the total number of times there was overlap, but not for any specific period.

I doubt I would easily be able to find this old file, so hope that helps get you started. In my case, it was a bit more complicated because as one unit went down, the count increased. When one went back into service the count had to decrease. You don't seem to need that.