No but u can still seperate stringed mobs by getting out of their perimeter. U sleep two, and pull other i.e a tonberry is pulled while u sleep the two cog oil slugs. U'll break the cog oil slug's aggro but you'll keep the tonberry's aggro cuz ur still in it's perimeter. The only reason y they seem to follow u everywhere is cuz as long as they follow u they'll be near u thus not allowing u to get out of the said distance.