For some reason I was thinking Forge did this already, but apparently not. I have a huge private (for now at least) 1.7.2 modpack I'm working on, and there are multiple types of the same ore from different mods spawning. For example, copper ore from IC2 and copper ore from Galacticraft. Popular modpacks I've played somehow merged the ore, so when the world generates, it chooses only one ore type to spawn.
Is there a public mod that can do this? Or did they make something custom just for their pack? Or 3rd option.. manually set the configs so only one mod creates said ore?