From a database of customer training appointments, I need to count the time
each employee works each day. One customer is scheduled with an employee at
a time. The current formula double-counts overlapping time periods.

Current formula:
=(SUMPRODUCT((Emp=382)*(Date=4/1/2006)*(Duration)))/60

The data looks like:
Emp Date Start time Min. AptID
382 4/1/06 9:00:00 AM 60 123
382 4/1/06 9:00:00 AM 60 123
382 4/106 1:00:00 PM 90 223
382 4/1/06 2:00:00 PM 90 223
382 4/1/06 4:00:00 PM 60 333
382 4/1/06 4:00:00 PM 60 333

210 Total Minutes

What formula would keep from double counting the same time period by
ignoring subsequent records with the same AptID?