removed duplicate function.

__init__.py

@@ -302,17 +302,6 @@ def adjust_sfx_volume(change):
                 channel.set_volume(left * sfxVolume * masterVolume, 
                                  right * sfxVolume * masterVolume)
 
-def adjust_bgm_volume(change):
-    """Adjust only the background music volume.
-
-    Args:
-        change (float): Amount to change volume by (positive or negative)
-    """
-    global bgmVolume
-    bgmVolume = max(0.0, min(1.0, bgmVolume + change))
-    if pygame.mixer.music.get_busy():
-        pygame.mixer.music.set_volume(bgmVolume * masterVolume)
-
 def play_bgm(music_file):
     """Play background music with proper volume settings.