Either 'wires crossed', 'deliberate mis-selling' or, as I suspect, complete ignorance of simple genetics - an all to common issue with some breeders. I think all breeders have a moral duty to do some research and actually find out what they have, what they are breeding and why and the expected outcome. (thank fully many do and I know enough to only but from those that do)
I have in the past been told by quite respectable shops, that carry a lot of morphs and rarer snakes all sorts of rubbish re: genetics. (e.g. this is 50% het albino meaning if you breed it you will get 50% of your litter come out albino

etc). Fortunately I know genetics, but I dread to think who many people fork out extra for normals (salmon sibs etc).
Don't get me started on Salmon phase boas that are cropping up on price lists at ten quid more than normals (is that a deliberate misleading trying to imply they are really cheap salmon hypos?) or 'Cooks tree boas' or 'red tail boas' or het pastel royals.
Inform the seller they are a muppet and give them a quick lesson in genetics.
Cheers
Andy