The plainbellies on Bloodred and Motley are not alleles. This was tried a long time ago, and it's mentioned in the Manual that the offspring had normal belly patterns.
However, I wouldn't consider it a bad idea to breed a bloodred to a Motley.
As far as the above hatchling... I have no clue. I don't think there's enough to go on yet. How many babies hatched from that clutch? If that's a motley, then it
should make the normal het for motley, or as per the previous "separation" theory, het for "Dorsal Motley." This means half the clutch (statistically) should come out expressing motley. (Or Dorsal Motley?)
If you got like 16 hatchlings and this is the only one of its kind, something needs to be looked into... If you get a bunch more with similar dorsal and belly patterns, it would also be interesting.
If you can, please post pics of the entire clutch (one dorsal, one belly for each individual) once it's done hatching out.
Nifty pattern whatever it is.

More than Motley, it reminds me of the patterns on snakes coming from Lavender lines. From the small amount of observation I've done, it seems like the radii of the circles are much bigger on a Motley. In addition, it has that hint of zigging often found on lav outcrosses...