Check out the original version of Kahin Door Jab Din Dhal Jaye from Anand. The Bengali song Amay Proshno Koray was originally composed by Salil Chowdhury and he reused the tune for the song Kahin Door Jab Din Dhal Jaye from Anand. Thanks to @FilmHistoryPic for this info.
Here is the original song Amay Proshno Koray sung by Hemant Kumar.
Here is Kahin Door Jab Din Dhal Jaye sung by Mukesh from Anand.