Right from Hollywood to Bollywood, it is quite common to have body doubles for all top heroes and they double for the hero for risky action shots. In cinema lingo they are sometimes referred to as Dupes.
Interestingly, Amrit Singh happens to be the son of Manjit Singh who acted as the body double for Amitabh bachchan in more than twenty films. Manjit was an assistant to stunt director Veeru Devgan, and because of his resemblance to Big B, he was always used as Amitabh’s dupe even by other action directors also.
This is a surprising coincidence that a father-son acting duo have another father-son as their body doubles.