As the OP, I don't mind. Hahaha.
I feel like the first few answers did a great job at answering the question. I think the differences I have seen mostly have to do with Hartmann's Mountain Zebra having the lighter stripes especially in the face. And I do think there is some natural variation even within the Burchell that explains some of what I've seen as well.
I do wonder because the one person said they have seen some turn from black to yellow from taxidermy. So if anyone reading this comes along and has had that happen with theirs, I would be interested in knowing because I think it's interesting.
No taxidermy mounts or hides should ever be in direct sun. Too destructive.This reminds me of a couple zebra mounts I have seen that a lot of it looked faded. I figured it might have happened from sun exposure.