Potentials Matrix report totals don't match up with summary report

Potentials Matrix report totals don't match up with summary report

I created a matrix report comparing Potential Owner with Stage (Stage History).  This gives me a great snap shot of where our sales team stands.

In order to validate the totals I created a separate summary report on Potentials.  I am grouping by Stage(Stage History).

For both reports I created a filter date where "Potential Last Activity Time" is set to "Last Week".

If I look at one particular BDM, in the matrix report I get a total of 53 records.  In my potential report I get a total of 71 records.

Why would there be a discrepancy between the two??  They are obviously pulling from the same database, for the same time frame??

A bit stumped on this one.