Man pages matching name al_get_separate_bitmap_blender in section 3alleg5:

al_get_separate_bitmap_blender.3alleg5.en	debian 11 / allegro5-doc
al_get_separate_bitmap_blender.3alleg5.en	debian 12 / allegro5-doc
al_get_separate_bitmap_blender.3alleg5.en	debian 13 / allegro5-doc