I have 2 digital cameras, a Canon SD 600 and a Panasonic Lumix TZ3 as a back-up. I noticed something strange when using the cameras for playback. Instead of playing back the photos in chronolgical order as usual, the order is often reversed, so the photos taken last, are shown first. I can't figure why this happens. Sometimes, the photos taken by the other camera aren't even shown at all. At first, they seemed to have been deleted but they miraculously reappear. My only fear is that one camera might delete the photos taken with the other camera. I try to use separate Memory Cards for each camera but sometimes I find it impossible.