"A Tale of Two Stans" is the twelfth episode of the second season of the American animated television series Gravity Falls, which was created by Alex Hirsch, and the 32nd episode overall. It was written by Josh Weinstein, Matt Chapman, and Hirsch, and directed by Sunil Hall, and originally aired on Disney XD on July 13, 2015.

Grunkle Stan tries to embrace his brother, who furiously punches him in retaliation for reactivating the portal. After a brief fight, Stan formally introduces Dipper and Mabel to his brother. It is revealed that Grunkle Stan’s real name is Stanley Pines, having taken the name “Stanford” from his long-lost twin brother, Stanford “Ford” Pines. Before federal agents locate the portal, Grunkle Stan takes the time to reveal his past to Dipper and Mabel, along with the secrets of his brother Ford.

In their youth, Stanley and Stanford were exceptionally close. Though Stanley was a slacker troublemaker and Stanford a straight-A student, Stanley protected his brother from bullies who mocked him for his polydactyly. The two often dreamed of sailing away to live a life of adventure. In high school, Stanford built a perpetual motion machine poised to grant him entry to his dream college across the country. A jealous Stanley accidentally wrecked the machine one night. Stanford accused Stanley of intentionally sabotaging him; the twins’ father, incensed that Stanley ruined Stanford’s opportunity to make the family rich, disowned Stanley. In response, Stanley vowed to make it big himself and become a successful businessman.

Eventually Stanford graduated from a less prestigious college and moved to Gravity Falls to study the anomalies concentrated there. He recorded his findings across three journals. With the help of his college friend Fiddleford McGucket, he built a universal portal that could lead to the home dimension Gravity Falls’s anomalies originated from. After a disastrous test run, McGucket left the project entirely, begging Stanford to destroy the portal. Meanwhile, Stanley’s attempts at becoming a businessman were disastrous; all his products failed, and he assumed fake identities after being banned from numerous states.

Wary of McGucket’s warnings, Stanford asked Stanley to visit him in Gravity Falls. Stanford gave Stanley the first journal and begged him to hide it far away. Outraged that Stanford had no desire to reconcile, Stanley fought his brother. In the process, the universal portal was accidentally activated. A bitter Stanley punched Stanford through the portal, which broke soon after. Plagued by guilt, Stanley spent the next thirty years attempting to re-activate the portal, which he only accomplished recently after finding the other two journals. To make ends meet and develop a cover story, Stanley assumed Stanford’s identity and faked his own death, turning his brother’s old house into a tourist attraction: the Mystery Shack.

Back in the present, the agents leave after having their memories erased. After an uneasy reunion, Stan and Ford work out a deal: Ford can live in the Mystery Shack’s basement for the summer to repair damage caused by the portal’s activation, but Ford has to stay away from Dipper and Mabel. An eavesdropping Mabel worries that she and Dipper will end up like Stan and Ford when they're older, to which Dipper assures her they won’t.

In a mid-credits scene, Soos calls an exhausted Wendy in the night to explain what happened.

The episode was viewed by 2.3 million viewers and received a 0.4 18-49 rating on Disney XD, a new record for the network,^[2] until Weirdmageddon 3: Take Back the Falls, the series finale, beat that record seven months later.