Het banana describes a gene pair made up of a banana mutant gene and a normal gene. Banana ball pythons are that way because they have a banana gene paired with a normal gene.

The belief that a het snake has a gene pair made up of a normal gene and a recessive mutant gene is a holdover from the days when all known snake mutant genes were recessive to the corresponding normal gene. Those days are long over. Herpers should get used to using the standard genetics definitions for homozygous and heterozygous.

Homozygous -- A gene pair made up of two genes that are the same. Two copies of the normal gene or two copies of a mutant gene.
Heterozygous -- A gene pair made up of two genes that are NOT the same. The two genes may be a normal gene and a recessive mutant gene, a normal gene and a dominant mutant gene, a normal gene and a codominant mutant gene, or two non-identical mutant genes.

I'd like to see the web page to have an opinion about it. But I'm interested in this sort of thing, and I have not seen anything that seems right to me. So I am pessimistic about that page.