Can someone check the NES rom for any more sound effects? In the NES game, if you buy a key, the game plays a darker version of the normal item fanfare, emphasizing low notes and bass, much like the Level 9 theme. (Apparently saying "ooooh you shouldn't have done that"😉
A tale of two item fanfares
That's just a consequence of the Rupee counter sound playing over the fanfare, blocking one of the music channels.
Furthermore, we at ZeldaClassic.com don't care for exactly reproducing the N2A03 chip's complex idiosyncracies.
Not a bug!