Display only duplicate values and delete UNIQUE Items

[Mistry]

I have large excel file - which has duplicate items in, I would like
to compare col A and Col B and if any of the items in apear in that
combination anywhere else in the colums then i want either a helper
col to show its is a duplicate or to highlight it in a different
colour. Ideally as as this will be done by may people ( who will not
follow instructions on how to do this ) i would like for them to just
open up a file and then press on a button ....

Eg:

A | B| Help Col
1 | 5 | Duplicate
2 | 6 |
3 | 7 |
4 | 9 |
1 | 5 | Duplicate
1 | 5 | Duplicate


Any suggestions?

 

[IanC]

I can suggest a way to do it with 2 helper columns, but you can hide column
C if you want.

I'm assuming your data starts in row 2 and ends at row 100.

In C2 put =A2 & B2
In D2 put =IF(COUNTIF($C$2:$C$100,C2)>1,"Duplicate","")

Copy both cells down.