In this clip, MG Sreekumar explains the story behind the song Devasabhathalam. The original take was done by Yesudas, Sreekumar and Sharath. According to Sreekumar, he kept up with Yesudas, prompting the music director Raveendran to  remind him that he is singing for a losing singer in the movie (played by Kaithapram) that he had to tone it down. Apparently Sreekumar’s friends advised him against it and so he opted out of the song. So in the movie, Kaithapram’s portion was sung by Raveendran while the casette had Sreekumar’s version.

There is a kind of similar story from 1968 when Kishore Kumar and Manna Dey had to sing in a competitive song called Ek Chatur Naar in which Manna Dey had to lose.

Wikipedia has the story of the song

Reportedly the song ‘Ek Chatur Naar’ (a duet by Kishore Kumar and Manna Dey) was partly improvised by Kishore Kumar at the time of recording and Manna Day, determined to show Kishore Kumar how he would sing the duet better (since Kishore had not been trained classically), got into the mood of the song and immortalized ‘Ek Chatur Naar’. Legend also has it that Manna Dey was upset by the fact that in the picturisation of the song, the singing competition between the two heroes (Dutt and Mehmood) was won by Dutt, for whom the background singing was done by Kishore. Dey didn’t like the fact that a classically trained singer like himself would have to lose, though only on-screen, to an un-trained singer (Kishore).[Padosan - Wikipedia, the free encyclopedia]

What both Manna Dey and Sreekumar have not realized is that film song is situational and the singing is meant for the scene and not every duet recording is meant to be a competition for the singers. Due to those songs no one finds Sreekumar or Manna Dey bad singers and in fact viewers understand the logic for the recording.

But Sreekumar seems to have become wiser as he is seen singing for a losing candidate in this competition.