I thought maybe I selected them by mistake before and unwrapped them with that part, so I deleted all textures and materials and started unwrapping that part all over again, and I was pretty sure that I unwrapped that part exactly. Once I made a texture again for it, the same previous faces catch that texture too. I kept deleting textures and starting unwrapping all over again many times, but no change that random faces catch the other part texture. It drives me crazy I don't know what to do. How can I tell blender that I don't want those faces catch any texture? I`m using blender 2.78
Thanks very much Sackadoo ... I found those UV maps and after I selected them I chose option weld from UVs menu .. The Textures and UV maps disappeared and those faces took the same material of it`s area which I wanted Since the beginning.