Responding to star George Sanders' complaint that his role of "modern Robin Hood" Simon Templar was becoming a bore, RKO Radio permitted Sanders to essay a duel role in The Saint's Double Trouble. This one finds Templar, aka the Saint, heading to Philadelphia to catch a gang of diamond smugglers. It so happens that the head of the criminals, Duke Plato, is an exact double for Templar (so guess who plays Plato?) Bela Lugosi is wasted in the role of a secondary hoodlum, though it is amusing to watch his double--take when he's confronted with two Sanders. Based on characters created by Leslie Charteris, The Saint's Double Trouble was the fourth entry in RKO's Saint series.
by Hal Erickson synopsis