I use the COUNTIF function to eliminate duplicate job applications.

Application serial number is in column A, each application ser# is 11 digits
Applicant SSN is in column B
Column C has formula =A1&"."&B1
Column D has formula =COUNTIF(A1:A15000,A1)

The problem that seems to have risen is that the COUNTIF function only looks
at the first 15 digits. What is happening now is we have people with similar
SSN's applying for the same job and they are being grouped together. Is there
a way to make COUNTIF look at the entire string of digits, or is there
another function that can be used?

Thanks for any help.