One thing that just came to mind, someone asked me what a .mtl files was. This a file that tells the client software what colors the obj is. This file is often generated while exporting a .obj and is used over a wide spectrum of client softwares. Ignore or delete this file, it is not needed for poser. For poser, the color assignments are set by the figure or prop file (cr2 or pp2) or the MAT pose assignment.