Howzit
THis should work. Put formula in cell H2
=IF(COUNTIF($B$2:$B$25,B2)=SUMPRODUCT(--($B$2:$B$25=B2),--($G$2:$G$25=G2)),1,2)
The formula broken down for informational purposes:
Count the number of orders relevant to the current row - Put in I2
=COUNTIF($B$2:$B$25,B2)
Using SUMPRODUCT...