When SPB committed a sin?

SP.Balasubrahmanyam known for his melodious voice won the applause of even renowned carnatic musicians like Balamurali Krishna though he never knew ABCD of carnatic music. SPB made his debut with ‘Sri Sri Sri Maryada Ramanna’ for which he received Rs.300 remuneration.Ghantasala who used to rule the industry during that time encouraged him a lot. Both sang many songs and after one song SPB came to know about a shocking incident after which he was tearfilled saying he committed a sin. He came to know that the song which was sung by him was originally sung by Ghantasala but since he couldn’t allocate more time due to his ill health, film makers completed the song with him. SPB said it was a sin committed by him inadvertently and this shows SPB’s respect for Ghantasala.