Why Your Shared Vaults Might Not Appear on Some Devices

1Password is capable of allowing the user access to multiple account. I've had quite a few signed in at times. Some folks use those same email addresses across accounts.

The Secret Key would be different between accounts as you mentioned. Shared vaults would only appear if you were accessing the account they were shared with.

If the password is the same across both accounts you can access both at the same time.