I think the closest thing you could get to something that was genetically ball python in certain parts and blood python in certain parts would have to be dual sired and BOTH a hybrid and a chimera. Chimerism really does have different genetics in different cells, but it's from two fertilized zygotes fusing. Hybridization is via the regular reproductive process so one chromosome of the pair from each, crossing over, etc.

So say you had a blood python mother mated with both a male blood python and a male ball python. Then, there were successfully zygotes from both the blood python mating and the ball python mating at the same time. These two zygotes then successfully fuse to create a chimera. That chimera would be blood/ball in some parts and pure blood python in others. One of these parts could then be the genitals. Of course, I could also buy a lottery ticket but I don't because it's pretty much not gonna happen.