Hi,
do you mean some devices are authenticated based on mac, others based on 802.1x ?
This is possible, since each auth request is just processed independent of the other.
Or do you want to authenticate 802.1x user only on "known" or valid mac-addresses (combined auth) ?
It is possible to "bind" a user to a mac-address (in the user properties), and as such, limiting the user to login through another device.
Doing this administratration is another thing however ...