Almost 5 years I have not used GA. I use Authy for the security of my account. I don't know if GA can be duplicated to other phones, but Authy can. You only need to remember the password with your email. I don't know this is a plus or a minus. Maybe if you lose your phone it will be easier to get backups.
With the latest update on google 2fa, you can make a QR code backup of the sites you want to. All you need to do is to:
- Open the google 2fa
- Click on the three dots at the top right corner
- Click on transfer accounts you want to backup
- Click on export accounts
- Making sure all the site you make authentication for are marked
- Then click on next
You will see a QR code, you can backup the QR code which consist of all the sites you selected and can be used on any new device to retrieve your 2fa authenticator.