Hey there Fooligan
Both accounts should unlock at the same time if you're using Face ID, so no, that's not normal behaviour. I'd recommend turning off Face ID in 1Password's Settings > Security, then lock and unlock 1Password (either account should be fine), and turn Face ID back on.
Then, when you've turned Face ID back on, tap the account and collection chooser (the icon in the top-left corner) and choose Lock. Unlock your passkey test account first, then tap the chooser again and tap your other account, unlocking it with its account password.
After you've unlocked both accounts manually, tap the chooser again and tap Lock. You should then be able to unlock both accounts using Face ID.
Let me know how that goes and we'll be here to help if you need us. :)
— Grey