The first corns the corn breeders called "hypo" were not hypo at all. They were line bred cornsnakes
I think you are confusing rosy or upper keys corns with hypos they are lighter than typical corn snakes and were once considered a sub species. The original hypos were a double recessive gene not line bred normals. The gene popped up in the mid 1980 in St Cloud FL.
Wouldn't Amelanism cancel out Hypomelanism? A Hybino morph is un-distinguishable from an Amel in Lampropeltis and Guttatas
You would think so but some specimens stand out like a sore thumb. Some of the other hypo strains bred into amels are very recognizable as double homo zygous animals look at a lavamel (Hypo C X Amel) they certainly stand out.
Later the true Hypomelanistics emerged where their black pattern was reduced to grayish.......I don't know what they call the first reduced black pattern ones now, but they shouldn't be Hypo
As I said those were rosies, Hypo is just called Hypo, Hypo B is Sunkissed, Hypo C is Lava, Hypo D is Ultra (Which is allelic to amel and will produce a co dominant phenotype in the F1 breeding similar to the Peanut Butter and T- in Floridana), Hypo E is Strawberry (allelic to Hypo A), and there are currently breeding trials to determine if Christmas Hypo is Hypo F or just one of the others that is line bred and since you have 5 test breedings to rule them all out it may take awhile.