Can i run two gdml files at the same time? how?

Hello Experts,
I want to know that can i run two gdml files at a time ?
for my case i have two gdml files in that one gdml contains all material definitions and world definition and in other one it contains object definition. it is just calling the name of material without defining the material because all material definition is inside the first one.
in this case how can i run these two gdml at the same time of the simulation.
Please help me with this. waiting for the reply!
Thanks in advance.