Perhaps something along these lines ..
(your subject line was lightly disregarded)

Source data as posted in cols A to C, from row1 down

Put in D1:
=IF(OR(SUMPRODUCT((($A$1:A1=B1)*($B$1:B1=A1)*($A$1 :A1<"")*($B$1:B1<"")))0,SUMPRODUCT((($A$1:A1=A1 )*($B$1:B1=B1)*($A$1:A1<"")*($B$1:B1<"")))1),"d up","")
Copy D1 down as far as required

Col D will check cols A & B and flag duplicates if any, as "dup"

Duplicates will be flagged either way, ie:

either:
x y
y x
(the 2nd line above is a duplicate - as per your post)

or:
r k
r k
(the 2nd line above is also a duplicate - as per normal interp)

--
Max
Singapore
http://savefile.com/projects/236895
xdemechanik
---
"ansoriano1" wrote:
I have a sheet of data dumped from a SQL query that is used to populate a
report.

Lets say that the data looks like this

A|B|C
1| x |y| Joe
2| r | k| John
3| y| x| Joe

I need a function that can look at the report, and where b1 = a3 and a1=b3,
then c1 is changed from joe to duplicate.

This way, Joe is only counted once, since for my purposes, rows 1 and 3 are
duplicate entries.

Thanks