Can Pind Daan be performed multiple times for the same ancestor?

Yes. There is no prohibition against performing Pind Daan for the same ancestor in multiple years or at multiple tirthas. Many families perform Pind Daan annually during Pitrupaksha as an ongoing expression of ancestral reverence. The Gaya Mahatmya texts describe this annual repetition as accumulating increasing merit for both the departed and the living family.