Authentication with different port and users

[Alan Kong]

Hi,
I used to have freeradius(old version) installed on Solaris and have 2 
separate processes listening on port 1812 and 1645. They authenticate 2 
groups of different users.
I upgraded and installed freeradius 2.1.11 on CentOS 5.6. According to 
radiusd.conf, I could get freeradius listen on different ports. Can I 
config the ports authenticate different groups of users using "/etc/passwd"?

Thank you.

Regards
Alan