For identical cells in column a, can I use conditional formatting to find dups in col b?

[Danielw2]

Hi, I have customer names in column a and names of products in column b. Is there a way to use conditional formatting to identify duplicate product entries in column b for each customer?

thanks!
Dan

[CAABYYC]

select B2
"conditional formatting" ->"new rule" ->"formula"
=AND(B2<>"",VLOOKUP(A2,$A:$B,2,)=B2)

choose color fill
adjust "applys to" range

[PietBom]

This CF formula will highlight duplicates:
=SUMPRODUCT(($A$1:$A$18=$A1)*($B$1:$B$18=$B1)*1)>1