Thomas & Friends S02E21 - The Diseasel

Based on the story of the same name from Main Line Engines.

Bill and Ben are tank engine twins who work at the China Clay Works. One day, they are surprised when they discover that their trucks have gone missing. They mistakenly believe that their trucks were "magicked away" by a "diseasel." Their crews formulate a plan and make the twins look identical to trick BoCo.