identify dups and color

[HPIMICHAEL02]

good day,

I'm trying to come up with a macros to identify duplicates in one column and match the second column code to ensure both codes match the duplicate number in column A, if it does not match then color.

attached in a sample, I have no idea where to start

Thanks

[6StringJazzer]

This does not require a macro. I used conditional formatting. Here is how I interpreted your question:

There are two columns of data. Values in the first column may be repeated. Normally we would expect that when a value in the first column is repeated, the corresponding values in the second column will also be repeated. If a case is found where the value in the second column occurs only once for a repeating value in the first column, highlight it.

=AND(COUNTIF($A:$A,A1)>1,SUM(IF(A1&B1=A:A&B:B,1,0))=1)

This formula first checks to see if the value in column A repeats. Then it checks to see if the value in column B corresponding to that value in column A occurs only once. It does this by looking at the number of combinations of A&B.

File attached.