How come she sometimes used quotes and sometimes paranthesis?

[FallenAngelII]

Most of Ayumi's CD put the name of the remix in brackets, like on singles, it's usually, like Beautiful Fighters "Original mix". The majority of her CDs uses this system.

But then, sometimes she just has to use paranthesis to muck this up, like with the Mirrorcle World-single, it's instead (among others) Mirrorcle World (Original mix).

Why? It's just confusing and inconsistent and forces me to check every single single's/album's back cover before labeling the songs.

How do you guys handle it? Do you just use quote marks for all songs, paranthesis for all songs or whatever you feel like at the moment?