Are the objects seperate objects or are you trying to texture one face of your house? You cannot texture only one face as far as I know. One thing that might have happened is that when you modified the texture on one thing, it did it to another thing b/c the second object was a copy of the first. After you duplicate objects, you must assign a new material to it. You should be able to see all the textures before the rendering takes place excluding things like fire and glows. Perhaps if you press 6 and display the textures in the scene view, you can figure it out.