Views show first image and show last image results in duplicate images in some cases.

I would like to show the first and last image from 8 image imagefields. To do this I have added 2 fields in a view: show first image, show last image.

This works as expected - except in the cases when a user has only updated 1 image - then the same image is shown twice. This is entirely logical - but not desirable.

How can I stop the second image displaying if it is the same as the first image? Some kind of argument code perhaps?