I wonder how come all those job quests NPC that was died in 1.0 still alive here and nothing mention about they die?

I first did WHM, nothing special here. But then I did WAR, I noticed those berserk brother appear again. Then I did MNK, that male monk which was the boss we killed at v 1.0 also appear. Now I heard the old Dragoon NPC also re-appear again too? Hoe does the lore handle this?