You may have an older version of Vengeance: Reloaded if you are only seeing one BATTLE track. Originally new tracks started at BATTLE B as naming it BATTLE A would mean it would play instead of the music already familiar to those playing Vanilla JA2, this way the original music is retained while new tracks are additional, not replacements. This has since changed only recently as the original JA2 BATTLE music doesn't quite gel with the newer tracks, and to me is too reminiscent of the Aliens movie soundtrack.

Later builds also added multiple tracks for not only BATTLE and NOTHING but for MARIMBAD and things like unique tracks for the credits sequence.

Regardless of all of this, if you are not using V:R you will want to follow the code or features in your chosen mod.