Maid Marian and Her Merry Men (1989)

Season 4: Episode 5

King John hires a man who is Robin's exact double to do bad things around Worksop, thereby discrediting him and the outlaws. However he is rumbled by Marian who persuades him to work with the merry men and a dead ringer for the sheriff and make Robin popular again. With the job done the look-alike sheriff gets somewhat carried away and heads to the castle to attack King John, making life difficult for his double.