Yes, and they are called Social Security Numbers.... or tax ID numbers.
These numbers are at least unique in the U.S.

At 01:31 PM 9/29/98 -0400, you wrote:

>     Numbers are used to uniquely identify an individual because there
>     simply is no real world adjective that is absolutely unique. I predict
>     that at some time in the future all babies will be tagged at birth
>     with their own "ID Code". I'm not happy about the prospect, but I
>     believe it will happen.