Duplicate Social Security numbers

Is there any way for Sage CRM to identify duplicate social security numbers? I'm running across applicants who have multiple employee numbers with the same SSN. Also, I'm having issues with identity theft, where multiple people have come in to apply with the same name, birth date and SSN. Thankfully we are a smaller company and I have a good memory remembering our employee's names. Otherwise we could have three John Doe's at three different jobs with the same SSN. The system recognizes duplicate invoices, it should recognize duplicate SSN's.

Any help you could give in this matter would be greatly appreciated.

Donna