Ahh!  Now I see what's going on.  A limitation of the Vlookup is that it will
return the first value that matches the lookup value you are using.

Try this function, which will overcome that limitation of the Vlookup:
=IF(ROWS(B$1:B1)<=COUNTIF($A$1:$A$20,$E$1),INDEX($B$1:$B$20,SMALL(IF($A$1:$A$20=$E$1,ROW($A$1:$A$20)-ROW($E$1)+1),ROWS(B$1:B1))),"")
This array has to be entered with Ctrl+Shift+Enter (not just enter)
Then, fill down as far as you need to...

This is a little complex, but I believe you can use it to get the results
you are looking for.  Notice a few things:
B-values represent the table array (product info and UPC numbers)
A-values represent the list of items that you are working with
E-values represent the one criteria that you are looking for in your list of
items.

Post back if you have any more questions.

Regards,
Ryan---

PS, here is another, similar, function that will yield the same results:
=IF(ROWS($1:1)>COUNTIF($A$1:$A$20,$E$1),"",INDEX($B$1:$B$20,SMALL(IF(($A$1:$A$20=$E$1),ROW($A$1:$A$20)),ROWS($1:1))))
This array has to be entered with Ctrl+Shift+Enter (not just enter)