This mostly happens at Satellite Dish but could happen at other locations. if you kill a loot barrel NPC will spawn underneath the prefab.
How I reproduced. Spawn loot-barrel with <bind m "spawn loot-barrel-1"> on the sat dish prefab and shoot them intell I got a spawn.
My guess is this might be a known issue but I thought I should report it anyway.
pro they will eventually despawn.