[pepsionice]

The next logical question is how many are collecting or possibly still paying into the pot? I don’t think we even want to know.

[Terabitten]

You have to understand how the SSA databases are set up. There is one database for identifying information, and another for payment info. The payment info database also has dates of birth and death, but THE TWO ARE NOT DIRECTLY CONNECTED.
In other words, all this means is that the ID database didn't get fully updated, likely back in the paper file days. The payment database is much more accurate, always has been.