He looked like two people combined together in bizarre fashion.
One of them had an extremely burly left side. Whether it was his left hand, left leg, or the left side of his torso and head, all were very powerfully built. However, his right side was withered up and shrunken. Because of that, he looked very misshapen and odd. The other person was exactly the same, except with the sides switched. His right side was powerfully built, and his left side was withered. When those two people stood together, they almost looked like a single person. Furthermore, their facial features matched perfectly!
Supposedly, Master Cloud Lightning used to be a single person. However, because of cultivating a heaven-defying magic, he failed in his attempt to break through to the late Deva Realm. The resulting backlash split him into two halves, each one of which contains a separate consciousness.
However, the twin Master Cloud Lightnings possess a secret magic that allows them to temporarily combine back into the true Master Cloud Lightning. When they do, his cultivation base rises to the late Deva Realm.