Responses
Well they're twins so maybe nacht just stopped bleaching his hair but I think he is a knight in his own right now otherwise he'd call himself morgen and really fake it.
In this flashback it looks like Yami was still in the aqua deer, he was young and clean-shaven, and no cigarette. Maybe Nacht rubbed off on him.
So morgen is dead, nachts use morgen appearance to become a knights and continue morgen life. Maybe morgen died because of devil too that's why he hate bad devils