Well if we look at the Branch site. It only has the single network and even with the overlapping destination network it shouldnt cause problem. If a host on the Branch network needs to connect to another local subnets host it will connect directly to it and the traffic wont flow through the router.
I am not sure if there should be any problems on the PIX side either.
But to be honest that is a very small amount of networks and I dont see a particular reason I would not configure each network specifically even though it would procude a couple of lines more to the ACL. I personally prefer to be as specific as I can in the configurations to avoid any problems.