The white one looks like it's filmed over/blinded, possibly by disease or injury, to me. :shrug: I don't see anything here I'd think of as evidence of heterochromia. Could go either way, but looks more like injury of one eye to me.
That's what it looks like to me too, but either way, it still seems to point to assymetrical eyes being an option, of course, it's possible that it's only available to NPCs too, but I don't think Bethesda would go out of a way to give an NPC such a unique feature and make it not available to play it unless the NPC in question was someone really important, which I guess this orc could be, since we don't know who he is.