Necessity is the mother of all inventions. The above mentioned song from Half Ticket was originally planned as a Kishore - Lata duet. Incidently, Lata was not available (out of town) and the recording deadline was urgent.
Kishore Kumar suggested that he will sing both the parts of the song. Initially, Salil Chaudhary was skeptical about it but Kishore Kumar convinced him.
The idea worked. The song is a comic piece where Kishore Kumar disguises himself as a woman and tries to romance Pran. The disguised avatar helped Kishore to lip-sync to the female portion while his co-star Pran lip-synced to the male portion.
The song turned out to be fine as Kishore sang admirably well in both the voices.
Image(s) Courtesy: Google.