Strange running total issue

I have not had this happen before.

I have data like this. I have a running sub total of $ amts and a COUNT of orders and then full totals for the salesperson.  In this case, it is doing the ABC correctly showing a count of 2. and for DEF it also shows correctly 2, but the full running total for orders for Joe, it's showing 3. one off, why would it do this?

Salesperson   Order type     Sales Amt.    ORDER#

Joe                  ABC             1.00            123456

                       ABC             2.00             123457

                       DEF             3.00             999991

                       DEF             4.00              999992