An interesting trivia since I brought up Mera Naam Joker. Everyone knows that the film bombed when released. Nothing new there. How many know that the film was re-released by Raj Kapoor's friend Mukesh (the singer), after I think 1 or 2 years, and it bombed AGAIN? What is more interesting is that the film was then re-released by another distributor, who went to make profits on the same 🙂
Re-releasing wasn't an uncommon thing in those days as unlike today, piracy wasn't rampant, so the films would usually release with a handful of prints in Bombay, and then based on response, the prints would be increased in subsequent weeks and they would very slowly go national.
----------
It was not dubbed, in fact voice of Amitabh was tweaked that way to make it more heavy voice.
I am pretty sure it was dubbed, though I would be surprised if it is what you say. Do you have some interview or something which states this? Amitabh himself had mentioned about it being a dubbed voice in one of his interviews in the 90s.