Following the web Tutorial 3 for Rollovers and Targets.
I duplicated all the rollovers.
Then I imported and duplicated the 1st target image. When I import the 2nd target image, instead of remaining over the 1st target image the 2nd Target image replaces the 1st Target image.
After duplicating the first image click on the page to deselect the image and then click on the duplicate you just created (the one at the top of the pile) then import the next image.
I suspect that after duplication you still had the bottom image selected so when you imported you imported the 2nd image into the first’s container.