Hum Kisise Kum Naheen (1977)

Rajesh belonged to a wealthy family his father turned all his savings from Africa into diamonds and hid it in a belt and was returning to India where he is followed by gang of smugglers he passes away due to heart attack and gives the belt to a stranger Kishorilal to give it to Rajesh.In order to escape from the smugglers Kishorilal hides the belt in a cycle tool box with initials as SK.Kishorilal and Ram Kumar had decided to marry their kids Sanjay (SK) and Sunita in childhood.But years later Kishorillal is a wealthy man and breaks his promise as Ram Kumar is still poor.Rajesh is told by Manjeet and Saudagar Singh that his diamonds are with Kishorilal and to get them back he would have to woo his daughter Sunita pretending to be as Manjeet.Sanjay starts to work as a manager for Rakesh and Sunita is about to meet him.He feels betrayal from Sunita as Rajesh entered her life and pretends to be him and both fall in love.But the truth soon comes out and Rajesh is also unaware that Saudagar Singh has plans of his own in order to get the diamonds.