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"Doppelgänger," a Gerry Anderson film, delves into the concept of parallel Earths. It explores the idea of alternate realities, showcasing a parallel Earth that is very similar to our own, yet strikingly different in subtle ways. The film's narrative revolves around the exploration of this parallel world and the interactions between the characters from both realities, leading to a captivating exploration of the nature of existence and alternate dimensions.