Can you explain how Sai Baba demonstrated his oneness with Lord Vitthal to his devotees?

Sai Baba provided several profound experiences to his devotees to show his connection with Lord Vitthal. As detailed in Chapter 4, when Das Ganu organized a Name-week (Saptah) and insisted that Vitthal must appear, Baba assured him that Vitthal's form would manifest, but emphasized that the devotee must be full of faith. In another instance, after Kakasaheb Dixit had a vision of Vitthal during his morning meditation, he went to see Baba. Baba surprised him by asking, "Vitthal Patil had come, right? Did you meet him?" and advised him to "Nail him down and make him steady." The proof was solidified when a picture seller arrived later that day with images of Vitthal that exactly matched the one from Dixit's vision, confirming Baba's omniscience and his identity with the deity.