The dwarven Fighter in my group I DM has a resistance to fire and necrotic, both at 5. They ran into a Deathpriest of Orcus, who has a ray that does necrotic AND fire. He hit the dwarf, and did 9 damage. Does the dwarf resist ALL of it (since 5 + 5 = 10), or does only the first 5 kick in, so...