try adjusting the aggro radius field in npc_types(I'm not sure if it even works), but I think the way aggro works in emu is once you aggro a mob, it checks for any other mobs in it's aggro radius, if there are they come.
But then again I know aggro is based off of line of site. For instance. Find a pillar or something similiar and put two mobs on one side and you on the other. If you aline yourself so you can only see one and cast on it, only it will come.
I think there might be a difference between walking into a mobs aggro radius and casting on it is what i'm getting at.
Therefore you may be able to fix it by making sure the mobs, even though they have a wall between them, are adequately far apart. You can also possibly try the aggro radius thing...
good luck
