As you may guess, that's not what you want.
The download url is the same, the returned image is not the same, it is also given different names, yet FDM still removes the previously downloaded image. Why would you want to do that when the filenames do not match?
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
If you first download:
http://bureaubladachtergronden.be/before/natuur/meadow-mount-california.html
and then:
http://bureaubladachtergronden.be/before/natuur/molokai-hawaii.html
or for that matter any other image from that site, FDM will complain that the download has already accured and wil replace the previously downloaded image.
As you may guess, that's not what you want.
The download url is the same, the returned image is not the same, it is also given different names, yet FDM still removes the previously downloaded image. Why would you want to do that when the filenames do not match?