Well for ex... if you could use another column adjacent to your data such that (based on example)

C2: =A2&":"&B2
copied down to C10

Then you could use the below for your total:

=SUMPRODUCT(--(B2:B10="A"),--(ISNUMBER(MATCH(A2:A10&":B",C2:C10,0))),1/COUNTIF(C2:C10,C2:C10&""))

This would account for multiple instances of Order:A