Is it possible to duplicate the passport prime using the same seed phrase and with magic backups enabled? If so, what will be the behaviour? Will they “sync” or cause conflicts? Particularly curious about things like security keys that rely on settings.
Short version: it’s technically possible to restore the same seed onto two Primes, but it isn’t a supported configuration and you’ll hit conflicts.
Sync model
Magic Backups push an encrypted settings + app data file to the Foundation server, identified by a hash of your master key. Sync is last-write-wins. If both devices push within a short window, the later upload silently overwrites the earlier one. No conflict prompt, no merge.
Security Keys
FIDO requires the authenticator to keep a monotonically increasing signature counter per credential. Many relying parties use it as an anti-cloning signal: if the counter goes backwards or stays flat across uses, the site can flag the credential as cloned and refuse it.
The counter is included in the Magic Backup, so in a normal lost-device-then-restore flow it carries over cleanly. The problem with two active devices is that each one tracks its own counter locally between syncs. Device A signs in to a site and ticks its counter up. Device B does the same and ticks its counter up from the same starting point. Whichever device’s backup lands on the server last overwrites the other’s state, and the relying party sees a counter sequence that doesn’t move forward as expected. That’s the exact pattern FIDO uses to detect a cloned authenticator, because functionally that’s what you’d have.
Other apps
Vault items, TOTP secrets, notes, and passkey records all live inside the same encrypted backup. Concurrent edits across two devices fall under the same last-write-wins behavior, so changes made on one device can be silently overwritten by the other’s next sync.
Bottom line
Prime is designed around one active device per seed. There’s no hard block preventing a duplicate setup, but nothing in the sync model is built to keep two of them in agreement.
Thanks! A sync system which allowed both to keep in sync would be an awesome addition down the line.
For testing and gaining trust in a device I routinely buy a second device and use the same seed for testing purposes…like to verify BIP85 is indeed recreating the same credentials from the same seed. There definitely should be some way to safely ensure we don’t accidentally overwrite all our backup data from our main key simply because we want to test things using the same seed on a second test device.
Hey @happy, that’s a completely legitimate workflow, and the good news is there’s a clean way to do it safely.
The thing to avoid is letting the test device sync at all. As above, the Magic Backup on our server is identified by a SHA256 hash of the master key, not the device. Two Primes restored from the same seed produce the same hash, so they point at the same file. With Magic Backups enabled on both, last-write-wins means the test unit overwrites your main device’s data the moment it syncs. That’s the scenario to dodge.
So opt the test device out of Magic Backups during onboarding. When you restore the seed onto the second Prime, tap Advanced on the ‘Create Magic Backup’ screen (KeyOS 1.2.1 and later) and choose a manual backup instead. Manual backups remove any link to your cloud and the Foundation server, so the test unit never touches the file tied to your main key. You can derive and verify BIP85 credentials on it as much as you like with zero risk to your real backup.
One thing not to do: don’t set the test device up with Magic Backups on and then toggle them off to “detach” it. Disabling Magic Backups deletes the Settings & Data file from the server (and the master key part on Envoy), which is the opposite of what you want when that file belongs to your main device.
Belt and braces: before you spin up the test unit, hit Back up now on your main Prime so its server copy is current. If you want an extra layer, export a Settings & Data backup file to an SD card and keep it offline.