Is there a reason why the B2 Normal Color, Deviant Pattern Dragons & Unicorns are the exact same as the B2 Normal Color Dragons & Unicorns? I've always wondered why they didn't change when everything else does. I've pulled the images up in separate tabs and flipped back and forth and nothing differs on them, not even shading.

it is the normal gene that gains the yellow star. A deviant normal pet looks just like the normal pet because there is nothing special about the pattern that you can make unique. With spots and stripes, you can change the style but how do you change a normal pattern to look deviant while still being normal?

Normal pattern means no pattern alterations (or basically no pattern). So even if a pet has a deviant modifier for pattern, it can't show itself in appearence because there's nothing to modify.