Good Cortex is the cut tenth-dimension Cortex from Crash Twinsanity, where an alarmed Cortex would accidentally disintegrate him with his ray gun after he welcomed him, Crash and Nina to the Tenth Dimension. It is unknown if he does battle with Evil Crash. Originally the Psychetron would malfunction when they arrived at the Tenth Dimension and their personalities get switched, and Evil Crash would have to hurt Cortex enough until he went back to his normal state. Concept art shows him in Rehab Lab with Evil Crash. He looks just like Cortex besides a backwards N and spectacles.
Cortex: (gravely) We must be careful. Any contact with our Tenth Dimensional counterparts could have dire consequences for all of existence!
A booming, friendly voice interrupts him.
Good Cortex: (warmly) Welcome to the Tenth Dimension!
Startled, Cortex draws his ray gun, spins round and fires. Good Dr. Cortex is disintegrated.
Good Cortex: (screams)
Dr. Cortex closes his eyes, mortified, as his counterpart crumbles into black ash. He opens one eye, expecting to witness the destruction of the universe. Nothing has changed.
Cortex: (beat) (shrugs casually) Forget I said anything.
A thought occurs to Dr. Cortex.
Cortex: (carefully, as it slowly dawns on him) Wait. If that was good Dr. Cortex, there must be...
From the shadows leaps Evil Crash, hunchbacked and feral.
Cortex: Evil Crash!
In the scrapped Twinsanity concepts, an Evil Crash drags Good Cortex through a ray.
After the scene,a reverse level would take,known as Rehab Lab,which was a reverse of the doc-amok levels (where Cortex gets chased by something and we have to rescue him),named as the Mock-a-Doc (where we have to hurt Good Cortex return to normal Cortex).