Excel check that value in column is always matches the column next to it

Question

I need to run a match but am unsure how to do it this particular way.

I have a sheet with thousands of ID numbers for each employee in column A

I then have a unique UID string in column B.

I need to make sure that every time value x shows up in column A the value next to it in column B is the same.

So if I have

1234 0987
1234 0987
1234 0988

It will flag the 0988 since 1234 is supposed to always have the same value to the right of it

Answer 1

You can do conditional formatting on the second column and make sure that every row below the first is equal to the first.

Eg:

=b2=b$1

Answer 2

[Edited to respond to question from OP]

Sort columns A, B and C (containing exceptions) using column A as the first key and column B as the second key. Then in column D in the second row of data (eg C2) put a formula like:

=IF(C2="Exception", "OK", IF(A2=A1,IF(B2=B1,"OK","BAD"),"OK"))

and fill down to the end of your data.

A more succinct version is:

=IF(C2="Exception", "OK", IF(AND(A2=A1,B2<>B1),"BAD","OK"))

You can then search by values for "BAD". Hope that helps.