When Sai Baba says he gave his Guru 'two paise,' was he referring to actual money? What did he mean by that?

No, the 'two paise' were not literal currency. As explained in Chapter 19, this was a metaphor for the two essential virtues his Guru desired. The text clarifies that the Guru had no desire for worldly money and asks, "what use did he have for gold?" Instead, the two paise represented "Faith (Nishtha) and Patience (Saburi)." By giving these two virtues to his Guru, the narrator explains that his "Guru-Mother was pleased with me." This act symbolized the disciple's commitment to the spiritual path through unwavering faith and steadfast patience.