RDS 2012 R2 - Allow Some Users Multiple Logon Sessions and Restrict Other Users to a Single Session

In Server 2012 R2 RDS, is there a way to allow some users to log on multiple times, but restrict other users to a single logon? On an OU or AD group basis?

I know there is a GPO setting under Computer Configuration for restricting users to a single logon, but this does not allow me to differentiate on a user basis (only on a per server basis).

Thanks,

James