This is inaccurate. You can't duplicate entry level devices like Yubikeys but hardware wallets like Ledger and Trezor both support backup of FIDO seeds in the

This is inaccurate. You can't duplicate entry level devices like Yubikeys but hardware wallets like Ledger and Trezor both support backup of FIDO seeds in the form of 24 english words you can store endless ways, or recover to a secondary device. I have duplicates of all my MFA keys. These devices are also more secure as they show you the website you are approving on screen to avoid being tricked by malware.