[eluser]Developer13[/eluser]
I'm not going to answer the "which is the right convention in the MVC approach" portion of the question. I do what works for me and for the application (which often changes), so I can't necessarily answer that part.
Generally, if the tables are closely related (as it seems your two tables would be), I would just stick them in the same model.
I'd also say to not get so caught up in the strict specifications of MVC -- just do what works