Are you talking about seeing stray clips on your timeline?
If so, what's happening is that you are adding new clips to your timeline by dragging them so close to existing clips on the timeline that you're inserting into them rather than adding new clips adjacent to them. This happens when you drag you're new clips or still too close to your existing clips on the timeline.
If you work in Quick View, you'll find this to be less of a problem. You can also just drag your new clips onto your Monitor panel rather than to the timeline and they'll be added automatically to the end of your timeline.
BTW, when working with photos, have you ensured that you've resized your photos to no larger than 1000x750 pixels in size (2000x1500 for HD)? Using oversized photos directly from a camera can cause some strange behave as well as overload the program.
I could have sworn that I replied to your question yesterday. What I remember writing included the following thoughts.
Until proven otherwise, there is no Premiere Elements 11 feature where you can identify Timeline duplicate photos in a large slideshow project where you have lost control over the content. It is easy enough to right click a photo in the Timeline and select Reveal in Media to find it in Project Assets. You could even use the Search field at the top of Project Assets to find a file in Project Assets, but, as for sorting out duplicates in the Timeline content, I see no provision for that other than
a. Stricter control over addition of media to the Timeline
and where applicable
b. Look into software to identify duplicates in the batch of photos that you are planning to import into Premiere Elements. I have never tried it, but I have seen mention of a program such as Thumbs Plus for such purposes.
Thanks for the tip about the size...this could explain why the software seems to stop and close down unexpectantly. I did manage to remove the space by deleting my soundtrack, doing the delete, then adding back the soundtrack. It was a pain, but I couldn't figure out how to get those clips, even though all were selected (by clicking each one with the shift key down) to move. I took the long way around, but finally got it. Thanks for your help!