Ok let see if I can explain this. I am trying to creat a photo montage with 20 or so pictures. I have created the master time line. Now I create another where I build my photo with a color background and I save it. Then I create another one an I bring them both into the time line and now I have the same picture. What's up with that?
How are you creating your comps - if you duplicate them in the timeline, then they are instances of the same comp. You should duplicate the comp in the Project window and then you get different compositions.