I have two mods which add an ore named copper. (Actually, I have seven.)
In Mod A, copper is a rare resource which can do a few important things.
In Mod B, copper is everywhere and used in everything.
If I use Mod A's generation, I can't play Mod B because I don't have enough copper.
If I use Mod B's generation, Mod A is too easy and powerful because there is copper everywhere.
So, I want to play Mod B with Mod B's copper and play Mod A with Mod A's copper. I don't want them to be interchangeable, because they aren't.
I want to turn off the oreDictionary.
Note: I still play with 1.7.10 (and so do a number of people). I support an option to turn off the oreDictionary in 1.10, but I also would be very grateful for a retroactive addition of that option to earlier versions.