Highlighting duplicate information within excel files

Please see the attached file

Regards,

Veejar

Sorry I didn't make myself clear the example I posted with some numbers and letters only simplified expression of problem to try and explain it in actual fact more along the lines of that attached.

Several files of 1000s of items with different serial number lengths (some blank) and with a part number (of different lengths and sometimes blank) that have to seprate out from information infront of it.

So I want to pick out rows where both columns are duplicates, such as 11 and 17. Ignoring rows where one column is blank.

Have tried with the following formulas in two new columns:

=IF(A6="","",CONCATENATE(RIGHT(B6,12),A6))

and

=IF(COUNTIF(C:C,C6)>100000,"",COUNTIF(C:C,C6))

And then filtered out the blanks and 1s from the final column.

But really I’m looking for something that will not only highlight which rows are duplicates, but also match them up together. To save me searching through all the duplicate rows.