Identifying duplicate lines using multiple values

Dan,

I'm not quite sure what you want...if you would like the duplicates to show the row of the original row then something like this:

=IF(MAX(INDEX((G$1:G1=G2)*(D$1:D1=D2)*(P$1:P1=P2),0))>0,"Duplicate of row " & MAX(INDEX(ROW(A$1:A1)*(G$1:G1=G2)*(D$1:D1=D2)*(P$1:P1=P2),0)),"")

There isn't an easy way to get a formula to list every row that is a duplicate in one cell, you'd really have to write some code in VBA.