Aida (1951) Film with Sophia Loren and Lois Maxwell, pt. 2 

Here, in Act 2 Sc 1, Amneris, played by the deviously sinister Lois Maxwell (with the voice of Ebe Stignani), tricks Aida, played by Sophia Loren (with the voice of Renata Tebaldi) into confessing her love for Radames. The lip syncing is so good, one scarcely realizes that it is not the actress' voices that one hears.