Validates that all spells have a different name.
Spell names are used for debugging in some places as well as an option for admins giving out spells, so every spell should have a distinct name.
If you're making a subtype with only one or two big changes, consider adding an adjective to the name.
"Lesser Fireball" for a subtype of Fireball with a shorter cooldown. "Deadly Magic Missile" for a subtype of Magic Missile that does damage, etc.