When you upload an image to replace an existing cover, ALL the images get replaced, not just the current cover image one sees on the search result landing page.
In the image upload form the label for the option says "Replace existing covers," plural, so I think the interface is being pretty clear. Do you think this continues to be a point of confusion?
(In reply to Owen Leonard from comment #1) > Do you think this continues to be a point of confusion? I guess not!