Not to nitpick...but lots of people have more than one passport. There are countries that issue you multiple passports to allow you to use one to go to country A, and another to go to country B, which won't let you in with a stamp from country A in your passport.
Also the more common case where a person has passports from multiple countries (eg citizen of multiple countries).
Also, technically, some counties allow infants to travel on a parent's passport (or they used to), although I don't think that data would be stored anywhere, I'd only seen it written in by hand by the passport owner.
This really shows how hard databases/user data can be, and that many assumptions (eg name/date of birth format/nature) have a lot of exceptions!
True, I appreciate the perspective as this is a blindspot for me as an American where "most" people have a single passport. Not that we can fly anywhere these days anyway :)
Ha. From what I understand, most Americans don't have a single passport. Nope, we can't, but neither can anyone where I come from either...they're trying to keep their zero cases zero.
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