The original file is "hw_16:10-4:3". This Wallpaper is for two screens, on the left one in 16:10 format, on the right one with 4:3. It is optimized for the Compiz-Fusion 3D-Cube with the settings "multiple cube".
The File "hw_4:3-16:10" is for two screens, too, but the widescreen have to stand next to the 4:3 screen on the right.
If you use only one screen, you can use the other two files.