Well, Abhijit Banerjee is one of the most famous music composers (often penned songs too) of Bengal. About him, no issues - we can discuss a lot. Next to all eminent artistes have sung his compositions (sadly, with the exception of Geeta Dutt).
As far as Shefalirani is concerned, I too am not quite sure. I was once in touch with Abhijit Banerjee - had I known about this record (of Shefalirani) I would have questioned him. Anyway, at this moment I am summarising what I know. I have come across the names of two Shefalis - Shefali Ghosh and Shefali Chakraborty. If I recall correctly, they were the same person, pre and post marriage. Shefali Ghosh has very few records to her credit. I've heard some of her Kirtans, also have one of her records. Shefali Ghosh had also sung with Pankaj Mullick, Utpala Sen, Tarun Banerjee and Manabendra Mukherjee, under Pankaj Mullick's music direction. Now, the scanned record cover of Shefalirani reveals that it was released in Puja, 1962 (1962 is typed out on the label, and I add 'Puja', as it was just Puja that year, when this sort of a label was used - with the star-sign, for all artistes singing under the Columbia label). No new artiste ever got to sing her first song or only song during Pujas, in HMV. Artistes of greater fame were preferred for records to be released during Puja. From this I feel, at least 1 or 2 of Shefalirani's discs must have been released before Puja, 1962. However never have I come across the name 'Shefalirani', before this. Interestingly, a record of one of Ratnadeep's songs, (1952) - Hindi version, mentions 'Sandhyarani' in place of 'Sandhya Mukherjee'. This may have been because, the MD Robin Chatterjee had always called SM Sandhyarani, out of affection (as SM has recalled in her writings). If this 'rani' maybe added to Sandhya Mukherjee's name as late as 1952, when she is quite a rage in Bengal, and a popular name in Bombay - why not to 'Shefali Ghosh' too (who really, was never a famous name)? This is just a hypothesis - at the moment!