Dear Balaji....

Except few, all others not give much importance for voice matching. Not only in Ninaithaaley Inikkum, but many movies.

For example: In the movie 'Johny', IR has used S.Janaki, Jency, Suthaja.... all sung for one Sreedevi. (Shailaja's song is not for Sreedevi).

In Kamal, Rajini movies also, one song will be by SPB, next one by Jesudoss and another one by Malaysia Vasudevan.

In present days also, MDs are using Hariharan, Unnikrishnan, Tippu, Harish Ragavendra, Shanker Mahadevan.. all for one hero.

There was a period they fixed TMS for Shivaji, MGR, Jai, Ravi and PBS for Gemini, Muthuraman...etc.

But it was broken by MGR in 'Adimai penn' by Aayiram Nilave Vaa.

In Ulagam Sutrum Vaaliban, he used TMS, SPB, Yesudoss all for MGR.