The second time Calvin used his Duplicator, he added the Ethicator, and thus created a duplicate of his good side. This duplicate was extremely well behaved, so much that Hobbes couldn't believe that people thought he was actually Calvin. This, however, backfired on Calvin when the duplicate started writing valentines to Susie Derkins. When Calvin found out, he immediatly began searching for the duplicate, trying valiantly to defend his reputation and principles as "Dictator-For-Life of the Get Rid Of Slimy girlS club". Eventually, Calvin confronted the duplicate, and they got into a fight. The duplicate, however, vaporized when he had an evil thought, thanks to a Moral Compromise Spectral Release Phantasmatron, Calvin unknowingly built into the Ethicator. When the duplicate explained that he was Calvin's good side, he frequently heard the comment "If that was true [he'd] be a lot smaller."
In Calvin and Hobbes the Animated Cartoon Adventures episode Evil Returns, Dr. Brainstorm revived him, the other clones, and some snow goons. He renamed Calvin's good side "Anti Calvin". He imprisoned them and Jack was forced to take over. After Dark Calvin's second death, he is now the co-leader of the clones, but he wants all of Calvin's friends and of course Calvin himself dead.