Different monsters that share a spawn area appear to have connected respawns. For example in Barrows where scaled fiends and fiery fiends spawn you can keep killing scaled fiends and eventually the area will only be inhabited by fiery fiends. It seems that there is a random chance for one or the other to respawn in the area and focusing down one type eventually results in a camp entirely comprised of the other. The same is true of shepherds and villagers in Lyonesse near Dunters.
I'm not sure if this would be considered bug or is just the nature of the Phoenix's massive camps. Either way it can result in a camp being almost entirely composed of just one type of the two mobs.
I'm not sure if this would be considered bug or is just the nature of the Phoenix's massive camps. Either way it can result in a camp being almost entirely composed of just one type of the two mobs.