Pivot table is doubling count

[Davdog]

I have a strange problem I haven't see before. I have a pivot table of test
results for about 20 stations. Each row consists of a station ID, the date a
sample was taken, the kind of sample, and the test result. I was looking for
duplicate entries, so I decided to use the count function in the pivot table.
For only one of the stations, the pivot table is reporting 2 test samples
taken on a single day, for every day that sampling ocurred. When I look in
the table of test results, there is only one sample taken that day (which is
what I expected). All the other stations are reporting the correct number of
samples and results.

Here is what the pivot table reports when I click on the "2" in a new
spreadsheet :
station date test epa code result
109041 8/30/1973 DO MG/L 300 4.6
109041 8/30/1973 DO MG/L 300 4.6


Here is whats in the data table:

station date test epa code result
109041 8/30/1973 DO MG/L 300 4.6

I have tried sorting the data table on all sorts of keys, I just don't see
the second entry...

Any ideas what is going on, and how to fix it?

Dave