how to setup GRE Tunnel over Two equal cost redundant paths

Hi everybody ,
I just wondered is it possible to set up GRE tunnels over two equal cost paths!I test it with real equipments but i didnt get to the point that i wanted ,here is what i did :
I connect two Cisco routers with two serial interfaces together then i create loop back interface on both of them, then setup tunnel interfaces but for the destination address i use loopback interface of the other router and vice verso ,the problem is that somehow we should add the other routers loopback interface into routing table,it doesnt work properly with static routes and with dynamic routing we should use PBR to force traffic into the tunnels,my question is ,is it possible to setup GRE tunnels over two paths ????