MUSICDEF doesn't reset lumps when going to a seperate page
This is an issue for mods that use vanilla songs in a different context as SRB2, such as Mystic Realm. The order is way off... My two suggestions are to either make something similar to Clear All in maincfg but specifically for MUSICDEF, or for the game to not take existing MUSICDEF properties in account when it's in a separete page.
