Here's a link to the original thread of discovery -
http://slickproductions.org/forum/index.php?topic=594.0Here's a summary:
In the original SNES version, healing multiple targets seems to include the dead in the split damage multiplier.
In the GBA version, healing multiple targets seems to factor against their magic defense, instead of ignoring it like does for characters.
I wish I knew how they botched this.
This would explain why more spells don't use the Cure spell set and have custom spells...