Why is that rotor housing that color and why aren't both??

the housings are from diffrent engines, that is why teh colors are diffrent the darker one usualyl means tha tthe oil hasnt been changed as often as well as diffrent type of oil and contaminants. basicly nothign to worry about.

Thats what a couple people suggested. Thxs Kahren

yeah someone used pensoil on the discoloured one