This doesn't really sound like a Photoshop issue so much as an operating system problem or a file versioning issue. Are you working on a network? Have you changed the names of the files a little bit at least?
You could try using the Image>Duplicate function if you're looking for an alternative approach but the same file naming and operating system issues apply.
I can't say that I have ever run into this myself, but this came to mind when reading your post. I don't have a clear and deep understanding of how this works and its implications.
What time period are we talking about here? Is this happening over several minutes, or straight away?
If you close all documents so you have the Start Screen visible, and recent documents is set to Preview rather than list, do the previews appear as you would expect them to?
That actually makes sense, I am working off a network. Is this a windows setting do you think?