Fun Fact - my older brother and I have sequential SS#'s. My parents applied for social security numbers for us both at the same time when we were kids when they opened savings accounts for us. My brother didn’t realize this until about 10 years ago, and at a family gathering the conversation came up about social security and I announced that when I retire I plan on applying for social security under ###-####-## (rattling off his SS#). The expression turned to bewilderment and he yells out…“How do you know my social security number!”
The year that SSNs became de facto required for children (1987) resulted in lots of families applying for SSNs for their entire brood all at once. I’d bet that sibs with sequential SSNs were pretty common among those folks.
My late wife and her sister were ~20 numbers apart. They were issued decades before the mandate, but probably processed at the same small state office where they were living in late childhood.
Same for me, although it’s all four of us sibs with sequential numbers. Dad applied for all of our numbers in about 1963, when I was 10 years old.
Heh. None of my 3 siblings knew this until four years ago, after our Mom passed away. I was handling the paperwork for transfer of the assets, and I told them that I knew all of their SSNs. They were amazed that I had memorized their numbers, until I clued them in as to how I knew.
… yes …
… which still isn’t a problem. The reason the pharmacist asks your DOB is because your name isn’t likely to be unique. Your identity is the culmination of absolutely everything attributable to you, but only a very small subset of information is required to positively identify an individual.
My sister and I do, too. We got numbers around 1975 or 1976, shortly after my parents bought a hardware store; I was 10 or so, and my sister was 7 or so. Our family had bought a hardware store, and my parents decided to be prepared for the eventually of formally paying us for doing some work at the store.
One day, my mother took us both to the local Social Security office, paperwork was filed, and at some point after that, cards came in the mail.
This has nothing to do with the problem we’re discussing here (reusing SS numbers) or the one that prompted this sub-discussion (reusing serial numbers in manufacturing). In those cases, you absolutely need uniqueness. If you reuse numbers and distinguish between different bearers of the same number (person, item) by adding the date of birth or production, then, for all practical purposes, that date becomes part of the serial number - you would never, ever use the number without the date for any purpose of any importance. In effect, you’ve simply added the date to the serial number, and you’re not actually reusing whole identifiers (consisting of number and date).
By way of a peripherally relevant anecdote: Germany has national ID cards with a machine-readable zone at the bottom, and there’s a long number in that zone. A bit detached from that number is a single digit. When I was a teenager, some kid at my school who considered himself knowledgeable spread the story that this digit would indicate how many people there were nationwide with your exact name and identical date of birth. I doubted the story even then because I couldn’t see a reason why the government would disclose this information and bother putting it on ID cards. I have since found out that the digit is a simple check digit, but if it were true it could be the basis for a cool way of unambiguously identifying people: “Out of all the John Herbert Does born on December 25, 1983, you’re number 4.”
Somewhat off-topic, as are most of my posts in this forum, but to me SOAP means an elderly HTTP standard, “Simple Object Access Protocol” which was used to transmit/respond XML data online via old-school.APIs.
A nightmare.
Thank the dark gods of the intermet for JSON, although that is not without its own problems.
When I was in HS, one of the teachers told me that they had once had two students with the same first, middle, and last names, born on the same day. They turned out to be first cousins (their fathers were brothers) and, in accordance with Jewish naming conventions, presumably named after the same recently deceased relative(s). You’d think they could have at least used different middle names, from their mothers’ family.
The school sorted them by the names of their streets. Mr. Eighth and Mr. Tenth, say.
Which is a good reminder that, even if you have a system set up so that coincidences are extraordinarily unlikely, sometimes it’s not always coincidence that you have to worry about. It was partly coincidence, in that two close relatives were born on the same date, but their names being the same was not a coincidence.
In other words, not all data is independent.
When I started working for SSA I found out that one of the people in my training class had a sequential SSN with me. At the time I had applied for my SSN when I was applying for my first job in the 1960s the local offices issued the numbers from a stack of pre-printed cards, and apparently he had been in line before or after me at the office.
Even further off topic, but our guide several years ago in Egypt, mentioned that half the males in Egypt were named “Mohammed” and half the rest were named “Ahmed”. (His name was Ahmed, his first son was called Mohammed, so when his second son was born, the doctor said “I guess this one is Ahmed…”) All Egyptians seemed to have identity cards, so I assume they have something similar to SSN to keep them all straight.
Local DMV offices work similarly with license plates. Each desk has a stack of sequentially numbered/lettered plates. Next!
It’s fun when you’re out driving and you see a plate almost the same as yours. Neener neener, I know what day you went to which DMV office! 
Australian medicare cards, which originally had a one or two year expiry period, have a replacement card number: 1,2,3,4, etc. It was always almost useless, and because of system changes, even less valuable now. The last time I used the card, I used the wrong sequence number, but it was accepted anyway. The previous time, I didn’t even have the correct card/sequence/expiry date, and it was accepted anyway.
To me, SOAP means a .. middle-aged .. HTTP standard, that replaced the elderly binary standard… all replaced now with secured/authenticated protocols (which has zero value to me, in my tiny niche of low-power items)