
nick1wasd |

There's no "type" bonus, it just says "When you beat the DC, knock it down by one more" so I'm not sure. They each have a bonus the other does not (Hardy gives poison resist, Fast Recovery gives more HP on a rest), so Paizo is kinda saying "hey, get both to be the unkillable super tank dwarf", so I don't see why they would NOT stack with each other.