l2tp turn off local user database
vpn_l2tp.php says when RADIUS is set "The local user database will
not be used."
and vpn_l2tp_users.php also shows:
"RADIUS is enabled. The local user database will not be used."
I don't see any configuration to turn "internal" off
(like "set auth disable internal").
It is not clear if this is about what type of users
like L2TP mdp.secrets or what?
But if is about mdp.secrets then that is used after RADIUS
and is enabled by default.
(I noticed this while working on my book.
My list of bugs is at http://reedmedia.net/books/pfsense/bugs.html )