The eye materials used in CC3 address this issue in that the texture has separate sections for left and right eyes. So I believe we are OK going forward.
Also some real folks like David Bowie have one eye blue and one brown ... and it's not as rare as you may think, as my son, father and grandfather can all guarantee personally, LOL. So it would be really great if we could use different textures for each eye.
+1 If a person got punched in the face, the skin around one eye would be bruised and the eyeball would be bloodshot. One eye, not both.