Duped

Duped is the second episode of Ben 10: Ultimate Alien, the second episode of the first season and the 100th episode overall.

Plot
The Forever Knights try to invade the museum using an alien paramilitary tank, but they're interrupted by Ben as Rath. Gwen calls Ben and tells him that he's missing Julie's tennis game. Ben sees the Forever Knights running away, gets angry, and tears apart their tank, then heads to the stadium for Julie's game. When Julie is about to begin her match, Ben shows up and makes a huge hit of himself and blows her concentration. Julie and Gwen get mad at Ben for showing up late. Kevin wants to investigate why the Forever Knights tried to rob the museum, but Gwen disagrees on going, stating that they're probably stealing some tech to rule the Earth. Ben also wants to catch the Sumo Slammers movie, but Gwen tells him not to. She tells Ben he can't be in two places at once.

Ben then comes up with a plan and transforms into Echo Echo and splits into three, then turns back and this time there are "three Bens". One of them is the "logical" Ben, the second is the "sensitive" Ben and the third is the "arrogant" Ben. However, he doesn't know this. The logical Ben goes to the Sumo Slammers 3-D movie, the sensitive Ben goes with Kevin to investigate the Forever Knights robbery, and the immature Ben stays to watch Julie's match. The Forever Knights, meanwhile, and their king Urian find a shortcut to the museum to claim ultimate power.

Unfortunately, immature Ben keeps embarrassing Julie, much to the annoyance of her and Gwen, sensitive Ben keeps annoying Kevin by blabbing about feelings, personal issues and tight subjects. Kevin then has it when he was talking how Gwen and him are together and Ben telling him since that his cousin and says that they might become a family...eventually Kevin says, "BEN, you've always been kinda girly, but today, you're CREEPING ME OUT!!!!" but the logical Ben is having a good time at the movies or at least so far.

Kevin and sensitive Ben fall into the basement of the museum and meet Urian and his Forever Knights. Urian makes his minions fight Intimate Ben and Kevin, where he's still annoying Kevin due to his personality, e.g. he says to Urian,"Excuse me, sir, but the signs clearly say do not touch the exhibits (holding up the sign)". They knock Urian's minions out and find out that he's after an Toltech Battle Armor, which he uses to attempt kill sensitive Ben and Kevin. This is sensitive Ben's fault, because he stalled Kevin, saying that enemies were people, too, while Urien assembles the Aztec alien battle armor. The sensitive Ben calls logical and immature Ben for backup. The two Bens hurry to the museum to help sensitive Ben and Kevin. When Kevin sees all three Bens, he responds with," If I wasn't running for my life, I'd demand an explanation!" Sensitive Ben and logical Ben try to explain, but at the end, immature Ben cuts them off by saying, to Kevin "What's it to you?" and Kevin repeats that he's running for his life.

Then, all three Bens change into Big Chill, Murk Upchuck and Cannonbolt to fight Urian but fail due to their weaknesses, differences as well as their confusion (Cannonbolt slips on Murk Upchuck's slime while Murk Upchuck gets frozen by Big Chill). So all the Bens change into Echo Echo, and go back into one Ben. Ben uses Lodestar to finally stop Urian. Even though Julie won the tournament, but was upset at Ben thanks to his arrogant clone embarrassing her. She kindly asks Ben to make it up for her by taking her to see the Sumo Slammers 3-D movie, but Ben tells her that he saw it during her match, which causes Julie to be very furious. She and Gwen storm off in disgust along with Kevin, leaving Ben all alone to repent for what he has done in order to gain back their trust.

Major Events

 * Rath, Echo Echo, Murk Upchuck, Big Chill, Cannonbolt and Lodestar make their Ultimate Alien debuts.

Ultimatrix alien debuts

 * Rath (Ultimate Alien debut)
 * Echo Echo (Ultimate Alien debut)
 * Murk Upchuck (Ultimate Alien debut)
 * Big Chill (Ultimate Alien debut)
 * Cannonbolt (Ultimate Alien debut)
 * Lodestar (Ultimate Alien debut)

Characters

 * Ben Tennyson
 * Gwen Tennyson
 * Kevin Levin
 * Julie Yamamoto

Villains

 * Forever Knights
 * Urian

Aliens Used

 * Rath (first reappearance; off screen transformation)
 * Echo Echo (x2)
 * Humungousaur (sensitive Ben)
 * Murk Upchuck (arrogant Ben; first reappearance)
 * Big Chill (logical Ben; first reappearance)
 * Cannonbolt (sensitive Ben; first reappearance)
 * Lodestar (first reappearance)

Errors

 * When arrogant Ben steps out of the bathroom, the black "10" emblem on his jacket is white and the 10 is in black text. This is one of the most common errors of the series.
 * Strangely, when Gwen is calling Ben, Rath suddenly pulled a phone out of nowhere even though he doesn't have pants on like Ben does. This is a rare moment of "Mallet Space", in which a character pulls an object seemingly from nowhere.

Trivia

 * Ben's middle name is revealed to be Kirby in this episode.
 * When the Echo Echoes turn into Ben, the personalities they display are similar to when Alien X is in use; Ben remains himself while his doubles are similar to Serena and Bellicus.
 * When Gwen was asking Arrogant Ben where he was after he exited the bathroom, he notes that this is a "Ben Classic". This is a reference to his arrogant and immature personality in the original series and the third season of Alien Force.