Interesting to me at least. Did you know in order to allow for more jobs- or something to that effect- it is against regulations for someone to be both actor and singer. So for all Bollywood musicals, the voices are dubbed with a different person than the actor singing. No surprise there. But the interesting thing is, for the sake of consistency each actor is attached to the same singer in every film. And vice versa- that singer can do no other work than provide the singing voice of that specific actor.