Hello Carl,
it won´t be a problem if you tell the router on the remote LAN to go out a specific interface for a specific IP address in the 10.0.0.0 range. The router will just look at the most specific route and send the packets there. So let´s say you have a PC with IP address 10.10.10.11 somewhere connected to the remote LAN. If you put a static route on the remote router, pointing to that IP address and out a local LAN interface, it wouldn´t matter wether the 10.0.0.0 address space also exists at the head office. In that way, IP routing does not really care where an IP address is, it just cares about the best path to getting there...
HTH,
GP