I have the following data set:

Month Item Salesperson
Jan B AA
Jan B AA
Jan B AB
Jan B AB
Jan B AC
Feb B AB
Feb B AB
Feb B AA

I am trying to write a formula that will count the number of multiple
sales by a salespersons that have had for Item B. In this example for
Jan and Item B it would be two (Salesperson AA & AB both had multiple
sales).

Thanks for the help.