Oh okay I see what's happening here - they're the same songs/sequence data rather than actual different/hidden songs, but the code is forcing all the music channels to use the same sample/patch/instrument (that jangly guitar-like sound). Ever tried listening to raw sequence data from NDS or N64 games? A similar thing happens because the incorrect midi patches are set. It's especially noticeable if the percussion is not on midi channel 10, so you get a bunch of out-of-key melodic notes rather than percussion. Try it if you like, the result will be similar to this.
I imagine a whole new goldeneye USF set would need to be ripped with this code activated. It'd work for most songs if not all... but eh, is it worth it to hear a bunch of screwed-up tunes? :P