I have installed the game as described here. (DosBox / D-Fend Reloaded on Vista)
 http://grandprix2.de/Anleitung/dosbox/eng_gp2_dosbox.html  and (german)  http://grandprix2.de/Anleitung/dosbox/gp2_dosbox.html.

No problem when I have only one GP2 Installation in the folder ....D-Fend Reloaded\VirtualHD\GP2
Two sounds folder -..\GP2\SOUND and ..\GP2\SOUND_org for example.
Now I can simple rename the folders and define which background music will appear in the game.

But it is more problematic when I have several GP2 Installations in the folder ....D-Fend Reloaded\VirtualHD\

I have for example three GP2's installed
....D-Fend Reloaded\VirtualHD\GP21984
....D-Fend Reloaded\VirtualHD\GP2LMS
....D-Fend Reloaded\VirtualHD\GP22010

I copy the Menu Sounds to
....D-Fend Reloaded\VirtualHD\GP21984\SOUND
start the game and .................I don't hear anything, no background music.

After renaming from
....D-Fend Reloaded\VirtualHD\GP21984\SOUND
to
...D-Fend Reloaded\VirtualHD\GP2\SOUND
everything works fine.

But now all GP2 Installations use the sound installed in
...D-Fend Reloaded\VirtualHD\GP2\SOUND

My solution:
In every GP2 Installation is a complete Sound folder.
In the folder GP2 is no game installed!  Here are my "additional SOUND folders for background music" installed.
The folder
...D-Fend Reloaded\VirtualHD\GP2\SOUND (at the moment with the 1984 background music)
and
...D-Fend Reloaded\VirtualHD\GP2\SOUND_original.  (with the original 1994  background music)

By renaming I can choose which background music I want to hear in all GP2 Installations.

AAS2010