I think you want something like this in C1:

=IF(ISNA(MATCH(A1,B:B,0)),"not ok","ok")

and then copy down. You could also put this in D1:

=IF(ISNA(MATCH(B1,A:A,0)),"not ok","ok")

and copy down to look for uniques in column B.

Hope this helps.

Pete

On Feb 18, 12:59*am, RNO wrote:
* * * * A * * * B * * * * * *C
1 * * * 30101 * 30102 * * ok
2 * * * 30101 * 30103 * * ok
3 * * * 30101 * 30104 * * ok
4 * * * 30102 * 30101 * * ok
5 * * * 30203 * 30101 * * not ok
6 * * * 30104 * 30101 * * ok

please help me for Cross matching A with B Vice versa by EXCEL function.