Please recount the incident with the two gentlemen from Goa as described in the source material.

Chapter 36 of the Shri Sai Satcharitra narrates an interesting story about two gentlemen from Goa who came for Sai Baba's darshan. Both men approached Sai and surrendered at his feet, feeling joyful. However, Sai's interaction with them was quite peculiar. He specifically requested a Dakshina, or monetary offering, of fifteen rupees from only one of the men, who gave it with joy. When the second man, on his own accord, attempted to offer a larger sum of thirty-five rupees, Sai Baba immediately rejected it. This display of apparent partiality greatly surprised everyone, including Madhavrao (Shama), who was present and decided to ask Sai for an explanation.