Why did Sai Baba accept 15 rupees from one visitor from Goa but reject 35 rupees from his companion?

The provided text from Chapter 36 narrates this curious incident but does not explain the reason behind Sai Baba's actions. It clearly states that two gentlemen came from Goa, and Sai asked for fifteen rupees in Dakshina from only one of them. When the second man offered thirty-five rupees on his own, Sai Baba immediately rejected it. This event is presented as a surprising moment that caused Madhavrao (Shama) to question Sai, implying the reason would be revealed later, but the explanation is not present in these source chunks.