In the college group song in Jugnu (1947), Rafi gives playback to many men including Dilip Kumar. He is seen himself singing too, for himself. However, for about 2 seconds, he is on screen. his lips are moving but the voice heard on audio is not his! So, somebody else gave playback for Rafi! Watch and listen.
Playback for Rafi in Jugnu (1947)
Now You Know!
Misc Songs 31