Splitting this issue off from
When a new version of an image is uploaded over an existing image and inserted into the page, the previous version is displayed in the RTE.
1) New Page->Rich Text->Insert Image->Upload image A.
2) Insert image A.
3) Insert Image->Upload image B with the same name.
4) Insert image B.
At this point, there are two images visible in the RTE - one was inserted before the image was replaced, the other was inserted after. They are both image A, they are both expected to be image B.
5) Enter a title and save the page.
The page now correctly displays both images as image B.