"can this income be added to S-Corp?"

Has he notified that payer with the info required for the S corp (using W9) and asked them to issue Corrected 1099 for both the personal info and the LLC info? I think you are describing two different EIN were used, which is why they issued two 1099? They can file corrected for those two; there is no need to send a 1099-NEC to the S Corp.