People also get multiple passports for things such as traveling to countries where having a visa from one in your passport would preclude you from entering the

People also get multiple passports for things such as traveling to countries where having a visa from one in your passport would preclude you from entering the other. Military service or diplomatic service often means you get a "black" diplomatic passport, which would have the same chip in it as any other e-passport. You can be sending one passport in to receive a visa (Russia, for instance, can take over a month), but you still need to travel so you're issued a secondary temporary passport. I'm sure there's dozens of other exceptions on why assuming every user has only one passport doesn't work out. (This is aside from the fact North Korea or China can just issue 10,000's of fake passports to hack this anyways)