there is no mojave in the black eye lucy or the ivory, but some ppl just want that one snake and dont plan to breed. some also just dont want to produce normals at all and with a super there is no guessing what you have or will have.
if you breed an ivory to a spector out of 4 eggs the odds would give you 50% superstripe and 50% yellowbelly. if you breed a yellowbelly to a spector you would get 25% superstripe 25% spector 25% yellowbelly.
also with a yb to yb sometimes you dont always get an ivory but with ivory to yb you will