DYK Amitabh-Rekha's first song was shelved?

Amitabh Bachchan and Rekha's first film together was "Duniya Ka Mela" in 1974, although Bachchan was replaced by Sanjay Khan after a string of flops. They had already shot a song together called "Tauba Tauba," which can still be found on YouTube. The book "Rekha: The Untold Story" by Yasser Usman reveals this episode and also...