AFAICT, the wide versions of solar-0-morn and solar-1-noon are exactly the same image. They aren't actually literally identical--they have a different md5sums at least--but I can't *see* any difference between them. With the standard versions, solar-1-noon has a yellower tinge to the light than solar-0-morn, but with the wide versions, both have the whiter light. (The differences between all 4 are also too subtle for me to really notice any change throughout the day anyway.)
What version do you have? I definitelly see same differences in the 1680x1050 wallpapers as in the 1600x1200 ones in solar-backgrounds-0.92.0-1.
whoops. i thought i'd just updated this machine but apparently that was my other machine, since I only had 0.91 on this one. Updating fixed the problem.