Calvin asks Hobbes to look at his newest invention. It's a box, sitting open on its side. Hobbes asks if that isn't Calvin's transmogrifier. Calvin says that it was, but he made some modifications. It's now a duplicator. It combines the technologies of the transmogrifier and a photocopier. Instead of a reproduction on paper, you get a real duplicate. Hobbes asks if their financial worries are now over. Calvin tells him counterfeiting is just one of its many uses around the home.

Hobbes asks if Calvin has tested his duplicator yet. Calvin is ready to. Hobbes asks what they should duplicate first. Calvin volunteers himself. He says Mom wants him to clean his room, so he can duplicate himself and let the duplicate do the work. Hobbes says he can picture the looks on his parents' faces when they find out they've suddenly had twins. Calvin thinks he can make a whole baseball team this summer.

Calvin introduces his duplicate. Hobbes isn't sure he's ready for this. Calvin tells his duplicate that he and Hobbes are going out to play. The duplicate will clean Calvin's room and do his homework. The duplicate doesn't like that. He runs off, telling Calvin to find another sucker to do his dirty work. Hobbes comments on how he is a duplicate of Calvin, all right. Calvin asks what he means. He says the duplicate is a total jerk.

Mom sees Calvin outside. She asks if she didn't just send him to clean his room. Calvin replies no. Mom brings him inside and says she did tell him to clean the room. She says she's losing patience for this game. Calvin tells Hobbes she must have seen his duplicate. They go to find the duplicate before he can cause any more trouble. In the bedroom, another duplicate walks out of the duplicator. Number two introduces himself to number three.

Calvin and Hobbes run up the stairs. Calvin says Mom must have sent his duplicate upstairs. Hobbes says this is turning into a mess. Calvin complains that the duplicate gets in trouble, but he gets the blame. They're horrified as they open the bedroom door. Hobbes says Calvin's duplicator is a big success as he looks at five duplicate Calvins. One of them says the duplicator burned out after the fifth one.

Calvin asks the duplicates what they've done now. They tell him to hide, because Mom is on the warpath. All the duplicates hide under the duplicator box when Mom comes in. Calvin smiles and tries to look innocent while Mom asks him to explain his behavior. From under the box, Calvin hears whispered a request to have a bigger allowance. Five times bigger. Calvin asks if he can get back to her on that issue.

Calvin is depressed that Mom read him the riot act. Hobbes whispers a suggestion to Calvin, who smiles. From under the box, voices ask if Mom has left, if the coast is clear, and whether they can come out. Hobbes says Mom is coming back again. Calvin tells the duplicates to be quiet. Calvin calls Hobbes a genius, as Calvin changes the wording on the box from duplicator to transmogrifier.

Calvin tells Hobbes he's perfected his duplicator this time. He says he added an ethicator. Now, instead of a complete duplicate of him, he's made a duplicate of just his good side. The good side duplicate does all the work, and Calvin gets all the credit. At school, the good Calvin raises his hand that he knows the answer. Miss Wormwood pats his head and says since he's gotten so many, he should let someone else try one.