But it's a hassle to have at least 2 yubikeys in case you lose one. And since you regularly sign up for new websites with OTPs, gotta keep them in sync. So always carry both with you. And if you carry both, then it's easy to lose both at the same time.

UPDATE: also gotta keep track separatelt of non-resident passkeys tied to Yubikey, because Yubikey doesn't know where it was used for non-resident. If you lose one yubikey, need to sync all passkeys to a new replacement one.

Would be nice if you could get an exact clone of a yubikey, so you always have a spare in case you lose one.

Though I think there is also the option that sites can store some sort of identifier on the key, then this would not work:/