Thanks for sharing!
Are you pointing out that the one on the right is more of a "black back" and so doesn't have the broken yellow dots down the back? I wasn't 100% sure that is what you meant by "dorsal markings".
I'm wondering if the key to the gene that causes "Mojave" isn't mainly the wide black pattern elements and perhaps also the quality of the yellow but perhaps the exact pattern and even some of the color quality could vary a lot from line to line. Just as some normals have prettier yellow than others and some normals have more fading in the center of their black pattern than others it could be that other genes that aren't directly part of the Mojave mutation affect the appearance Mojaves.