Help! Custom Spells Trigger default spells too!

My custom heroes have custom spells that are altered copies of default spells. If the hero is in a group and the custom spell is activated, the default spell is activated as well, even if the hotkeys and text order strings are different!

How do I fix this?

For example, custom hero Firebat has a spell Napalm Strike, copied and altered from Flame Strike. If the Blood Mage is in the same group when I push 'N', he'll cast Flame Strike instead of the Firebat casting Napalm Strike. This is a particularly irritating problem for me, since everything i've tried seems to have no effect.

PLEASE HELP!!
-MD

Im pretty sure that changing the order strings has no effect. I was aware that having 2 skills based of the same skill will cause this problem, but not that units grouped have it.

Weird... o_O