This is a story that I heard from my grand aunt Smt Rukmini Rajagopalan almost 30 years ago. Sometime in the fifties GNB had just begun singing Kamalambam bhajare in concerts. He had sung the song in a concert at RR Sabha, and again in a sabha in Egmore (probably the Jagannatha bhaktha sabha) and repeated it in a concert in Tambaram. My grand aunt being a GNB fan had of course heard all the three concerts, in the space of about 2-3 months. GNB was due to perform on the radio, and my grand aunt specifically sent a message to GNB asking him to avoid Kamalambam bhajare in the programme! As it so happened GNB did sing Kalyani and Kamalambam bhajare in that concert as well!
Later when they met my grand aunt enquired as to why he sang the same song. GNB had only this to say, "Mami, I sing at 3 different places in the city and a radio programme that goes out to so many others who haven't even attended those concerts. If you choose to attend all those concerts, I cannot do much about it!" My grand aunt told this to me when I was reluctant to repeat songs early on in my career. She explained this story and said that it is important for you to sing a song repeatedly at different venues to get a better grip and the rendition is bound to sound better everytime you sing it!