Fixed passcode is not a 'mode', it is 'another authenticator in addition to what the user already has' (or doesn't have).
Any user can have multiple authentication methods assigned at the same time, and any or all of them can be used, at any time.
A user might have: three different tokens, each with it's own pin, a fixed passcode, and on-demand all
at the same time...any one of those would work if the user entered the correct code(s) for one of them.
So, it is expected that if a user has a token and a fixed passcode, either one will work, until one is disabled, removed, unassigned...etc.
