Man pages matching name allegro_audio_pan_none in section 3alleg5:

ALLEGRO_AUDIO_PAN_NONE.3alleg5.en	debian 10 / allegro5-doc
ALLEGRO_AUDIO_PAN_NONE.3alleg5.en	debian 11 / allegro5-doc
ALLEGRO_AUDIO_PAN_NONE.3alleg5.en	debian 12 / allegro5-doc