Many people over age 60 and some over 50 have duplicate #s. This happened in the 50s when wallets were sold in the US with 'sample' SSN cards. People buying those wallets thought those were their number. Most of these are probably out of the system by now, thanks in large measure to Mediare and Medicaid.In the US each person is suppose to have a Social Security Number (SSN) however this number may not be unique as there have been cases when the USG has handed out duplicates.
It is integrated into our birthing system that a person is assigned an SSN at birth howeverOnly recently, since the IRS required SSNs for all dependents on the 1040. I remember the year that I got my 3 oldest kids their #s to comply with the new 1040 regs.
births outside the system (e.g., home births) this isn't the case and
a SSN may not be obtained for years.
I believe in the Federal Witness Protection Program one can get a new SSN. Finally, I don't know if it is true,
It is. There are other ways to get new SSNs too.
If you never file taxes and pay cash for medical care and avoid banks, you can do quite nicely without one. Met some people in the hills of Tennessee some years ago. Their family has avoided all of this since 1792....I am told one does not have to have a SSN however the US system is structured that you do (read: life is a hassle).