This article or plot contains spoilers from the actual game. If you do not wish to be spoiled, do not read it.
Alternate Universes Collide Again is a mission in South Park: The Fractured But Whole.
Head over to Kyle's House, interact on the front door and meet up with Human Kite, who'll tell you that his alternate universe counterpart is back and at the house's backyard. Go there to see a brief cut scene leading into your second battle with the Human Kite from an Alternate Universe - note that you won't be able to use Human Kite for this battle.
Battle: Alternate Human Kite: Redux
Initially, Alternate Human Kite will be straight across the battlefield from your team, protected by two columns of obstacles while he bombards you with his eye lasers; they hit in a cross formation, and can attack any tile on the battlefield, so try to keep your team from clustering together too much. Since your allies don't have many ranged attacks, you'll have to attack the obstacles to reach your target; moves like Fastpass's Blind Side or The Coon's Coon Lunge can help cut through them, or Captain Diabetes can use Sugar Rush and Insulin Shock to build some Protection off of them. Also, make use of your Timefart Glitch power, this will completely stop Alternate Human Kite's laser attack for a turn. Once you're past the barricade, Alternate Human Kite won't be much of a problem...but that's only the first phase of the battle.
Battle: The Broflovskis
Once Alternate Human Kite is beaten, he will try to call upon "the power of the wind", only to have his kite blown away and stuck in a tree. Unfortunately for Coon and Friends, he has a backup plan: calling in Kyle's mom for backup. She is a close-range bruiser with a basic melee attack and a rush attack similar to Coon Lunge or Sugar Rush, but she is rather weak......in her normal state.
The original Human Kite will join the fray once his mother takes damage, but you can mostly ignore him unless his eye lasers and Kite Shield prove too annoying; to win the battle, you only need to take out Kyle's mom and Alternate Human Kite. Although it's tempting to take out Alternate Human Kite first, since he has only 1 HP (and he'll shield himself for 180 HP on the first turn he gets), it's better to focus on Kyle's mom; if the younger Broflovskis are injured, she'll go berserk and move after each hero's turn (that's up to 6 turns per cycle)!
Upon defeating Kyle's mom and Alternate Human Kite, the battle will end; you will be rewarded with the Driedel of Vengeance artifact and the Maximum Jersey DNA slot.
Once the Broflovskis are defeated, Kyle's mom would angrily threaten to call the cops to have the kids arrested, but Human Kite stops her action and confesses his wrongdoings. Seeing her son being apologetic, she forgives everyone under one condition: get her nephew's kite down from the tree. Open Inspection Mode to scan the backyard, specifically, a pinwheel. You will then have Human Kite climb onto your back, carrying you via fart-powered jumps. Use your newfound ability to reach the kite in the tree. Upon landing down after retrieving the kite, Human Kite will come up with the name for the ability: Fartkour. Proceed inside the house to return the kite to Alternate Human Kite.
Once the kite is returned, you are able to take selfies with Alternate Human Kite and Kyle's mom.