(Context: the 2024 Parliament elections in India, for the constituency of Kollam. The numbers in brackets are lead, not change from last election. Source: Election Commission of India)
It'd be funny if they were eg. Revolutionary Socialist Party and Socialist Revolutionary Party, or Communist Party of India and Indian Communist Party. Now it's just… well, two parties with very different names and different politics (socialism ≠ communism) (edit: see reply comment re politics of the RSP)
RSP is a proper communist party, with it's root in the HSRA, the original revolutionary communist party in British India. Communist parties break away a lot, because they disagree with each other. Coming with names is hard, because they're already taken, so they have to use the word related to 'socialism'.