This is genius filmmaking! When the movie Indiscreet came out in 1958, it wasn't accepted to even shown a married couple together in bed. To be able to film the romantic bed conversation between Cary Grant's and Ingrid Bergman's characters, film director Stanley Donen solved the dilemma by employing a split-screen effect:
As noted in a May 1958 Hollywood Citizen-News article, the film employed a split-screen effect showing Philip and Anna in their separate beds in different cities. According to the article, Donen had "two bedrooms built side by side on the sound stage, and...two separate camera and sound crews. Their operations were synchronized, but each color camera photographed only one-half of the action." Although the characters are supposed to be three hundred miles apart, the effect resulted in their appearing to be "side by side in bed." This was significant in 1958, when even married couples could not be shown together in the same bed. Because the actors could hear each other's words as they were spoken, "their emotional reactions had far more romantic impact than if the action of each split-screen half had been staged at different times." The Hollywood Reporter review describes how the act of Grant straightening his blanket in Paris appears "to conquer space by patting Bergman's London derriere." The Hollywood Citizen-News article predicted that this method "might well set a precedent for future scenes of this kind."
Via And So It Begins.