I have done some searching, didnt find anything that talked about this issue, though I have to doubt I am the first one to notice it.
I have started using image uploads in my posts. It's easy enough, might as well. But while I was giving my site a once over, I noticed a pic that did not belong where it was. After a few moments, I made the following realization...
The pic that was wrong, had the same name as another pic that was newly uploaded.
I get most of my pics from my own collection, from my digital camera pics. So I upload pics named PIC0001.JPG or PIC0006.JPG, I never change the names.
It just so happened that I uploaded 2 files named PIC0008.JPG in this month ( April ). So it would appear that when I uploaded the 2nd PIC0008, it replaced the first one I had previously uploaded. This wouldnt have been a problem if I had done this in different months, but as luck would have it, they were in the same month.
This might be an unintended feature, I dont know.
I might suggest simply renaming the files as they are uploaded. Change the file name to the timestamp, this way they are all unique. Maybe if I get ambitious I will pour through the upload functions and make that hack myself. If anyone shows any interest, I can post back with changes.