the reason this happens is that c2 considers your 2 "enemy's" instances as one.
many reasons for that.
one solution would be to add " for each" -it is under the system commands" this way c2 will react to "each" lol.
if you are using an invisible square sprite and on top of it your enemy's sprite then you must add both in a container.
this way c2 will treat each instance as separate.
if you could post a .capx i would be able to help you more specifically .