At the beginning of Chapter 62, though, we learn that McGonagall has faced Voldemort four times:
“She had encountered the Dark Lord four times and survived each one, three times with Albus to shield her and once with Moody at her side.”
This makes it likely that Dumbledore has faced Voldemort on other occasions without her.
I noticed that the MediaFire link for the PDF version is dead—is that still being actively maintained?