I think the answer to your question is 'yes'. You can hold multiple offers from a TMDSAS school and from an OOS school. Here's the link to the TMDSAS site:
http://www.utsystem.edu/tmdsas/medical/acceptance_Match_info.html#PreMatchOffers
Here's the quote:
Applicants may hold offers from one of the TMDSAS medical schools as well as other non-TMDSAS schools such as Baylor College of Medicine. By May 15 of the matriculation year (April 15 for schools whose first day of class is on or before July 30), each applicant who has received an offer of acceptance from more than one school must choose the specific school at which the applicant prefers to enroll and withdraw his or her application from all other schools from which acceptance offers have been received.