Was this is the US?
There are benefits to having a national, public, unique ID # for each person and this is one of them; it reduces the number of 'they had the same name' mistakes to nearly zero
According to the Social Security Administration:
> At its inception, the SSN's only purpose was to uniquely identify U.S. workers, enabling employers to submit accurate reports of covered earnings for use in administering benefits under the new Social Security program. That is still the primary purpose for the SSN.