So, I've found many posts about how this part of the dhampir worked in the first printing, but in the Player Core 2 it appears to be worded differently and I have yet to see anyone else comment on it. It says they have the void healing ability, but doesn't reference it being in the Monster Core, and it specifically states that you are harmed by vitality damage and healed by void healing, but stating nothing about the inverse.
As of right now I'm ruling it in my game as though the dhampir character is both living and undead, being harmed by vitality and void damage, and being healed by both healing effects. Is there anyone out there that has a more concrete answer that isn't just referencing the posts made before Player Core 2 released?