After all, it's estimated that there are 40,000,000 dupes out there.
This is a misconstrued / misused statistic.
The linked page at idanalytics.com says:
More than 20 million Americans have multiple Social Security numbers (SSNs) associated with their name in commercial records according to a new study announced today from ID Analytics, Inc., a leader in consumer risk management. The study also found that rather than serving as a unique identifier, more than 40 million SSNs are associated with multiple people.
[bolded by me]
That is also poorly worded. What association are they referring to? I'm VERY confident they do NOT mean the official SSN database. FWIW, one can verify SSN's using the social security system's SSNVS (social security number verification service): https://www.socialsecurity.gov...
I suspect they mean that SSN's that show up in external databases, such as employment records, fraud reports, credit checks and reports, etc (anything falling under what they called "commercial records", and what they base their bread and butter business on), and that those end up having multiple names associated with them - which makes sense. since there's probably a LARGE amount of typo's and purposefully incorrect information.
This is quite different than the subject of this article, where two women had the same SSN issued to them by the Social Security administration.
FWIW, if you're wondering if they're ever re-used, they have not been thus far (you take your number with you when you die, so to speak). There are currently about 319 million people in the united states. The SSN format has room for a maximum of 999 million numbers. There are a bunch of exceptions that won't be used:
* 100 million of those are reserved for ITIN use (ITIN's start with "9").
* No number group will ever be issued all zeros (ie. 000-nn-nnnn, nnn-00-nnnn, and nnn-nn-0000 are all invalid), which rules out a bunch more.
* Area number 666 has never been issued, and probably won't be (ie. 666-nn-nnnn), ruling out another million of them.
* Numbers from 987-65-4320 to 987-65-4329 are reserved for advertising use.
* Hilda Whitcher's SSN is now invalid (http://www.snopes.com/business/taxes/woolworth.asp)
To date, over 450 million SSNs have been issued, and the SSA notes that it does not reassign SSN's after the number holder's death (https://www.ssa.gov/history/hfaq.html). I don't know where the countdown clock is for running out, but we'll get there eventually (we're over half way there). That's going to make one hell of a y2k, unless they just start re-issuing from the death master file (yes, that's a thing).