hello flavio and welcome to simplymaya, i think your just adding a texture to one sphere and changing one of their material/color options which then which then is leading both of them to change, if im on the right track to resolve this issue, do this: right click on sphere1 go to Materials Assign new Materials then choose "lambert" and so forth choose your texture/picture then for sphere2 repeat method 1, do not just click on the checked box because you will edit sphere1 if you get what i mean, marlon