¿Quién soy yo? (1970)

Mario Colomer, prime minister, is burdened by overwork. His problems seem solved when his assistants tell him about Juan Brandel, a possible substitute, just like him physically, but with a funnier and more adventurous personality. At first the plan seems to work and the politician begins to gain popularity. The plot thickens when the 'original' becomes jealous of the 'copy' and the substitute exceeds his functions.