Internal and external membership logins

Is it possible to have two separate membership area linked to my website?

We have a membership area for paying members but are curious if we could set up a separate Free membership site for internal usage. 

This would be a password protected web based access portal to training information and we would want it kept separately from our paid membership portal that is public facing as well as separate from our public facing site. 

What membership level would be necessary to achieve this?