Here's my example:

A B Qty Total
d y 2
d z 3
e x 4
e x 10
e x 11 25
e y 5
f x 1

I want to add the numbers in the Quantity Field, but only where you have
duplicates. For example, in this case, QTY 4, 10, 15 would be added in a new
column "Total" as Column B's "x" was the same for every Column A's e. No
other additions would take place. The database has 5,000 rows and sometimes
there are two duplicates, but other times there are 10 duplicates, so I
haven't been able to do a sum product. I tried =IF(B4=B5,SUMPRODUCT(D4:D5),
0) but this only added two rows, not the 3 rows together.

Many thanks!