2 instances of ssh

["J Adams" <pacetownsley gmail com>]

I want to run two instances of sshd, one that authenticates against system accounts and another that uses radius. How do I tell Pam which conf file to use for two instances of the same service? Is that possible, or do I have to run one instance and one file that checks both places? If it's the latter, how do I do that ("sufficient" doesn't always seem to behave as I'd expect.)? Help is greatly appreciated.