No, I believe that a true buckskin by definition does not have a dorsal stripe. Duns are far more varied in color, but they are required by definition to have a dorsal stripe. Some people will call horses "buckskins" even if they do have a dorsal stripe, but they're not technically buckskins by definition :)
Buckskins can have a dorsal but it can because by sooty or the dun gene depending on the parentage or the horse and what it looks like you can usual tell the difference.
Dun dorsals have a crispness to them and are distinguishable from the body. Jackpot is double diluted so his dorsal isn't extremely dark but its still crisp and easily seen.
My buckskin dun
Many horses that have dorsal stripes are NOT dun. It is called countershading. Dun not only has a dorsal, but also other factors including leg bars, a diluted coat color, and sometimes other dun factor. See this thread: Difference between sooty and dun
to the person with Jackpot - isn't a double dilute a cremello or perlino?
That is where the confusion comes in with calling the creams "dilutes" for so long, when there are other dilution genes in horses too. Jackpot is a double dilute in that he has one copy of cream, and at least one copy of dun, both of which are dilution genes.