[bliblah]

This is very accurate, countries do not share citizenship data so it is impossible for them to know who has 2 or more passports.

I have several friends that have remained in possessions of their previous passports and still renew them in case they ever need them.

[rockinghigh]

No, it’s highly dependent on the countries involved. When you apply for the second citizenship, that country knows about your first citizenship. They can decide to force you to choose one. And the first country may or may not allow you to give up that citizenship. As an example, you can read about dual citizenship in Europe here: https://m.dw.com/cda/en/dual-citizenship-in-europe-which-rul...

You will see that the rules differ by country.

[bliblah]

You misunderstand. The USA does not have a list of Japanese Citizens, meaning that if a Japanese citizen decides to become and American one they have no concrete proof that he discarded his proof of Japanese citizenship (in this case a Passport) unless they reach out to Japan.

Unless you are an international criminal the US will not waste time or resources requesting that information.

This is true for most countries.

[mvid]

Yes, but I believe the point is that you can lie that you gave up the first one, even if you didn’t. There isn’t a way of checking

[Xeago]

There’s quite a few territories where you need to get a license/seal/stamp/signature from the administration of your current citizenship. Going deeper, it’s then common for that request to only be authorized given the promise of the administration of the new citizenship to grand you this new citizenship. A two-way commit of sorts.