Even if I can understand that two seaters, when in formation, don't make evasive manoeuvers their own way, it is much more problematic and unrealistic when you fight lone or small group of two seaters (quite often in 1915, much rarer later : and that is another problem ). During my 1915 Esc 12 career in MS, the only difficulty to shot down two seaters, was to gain the good position, then just press the trigger while the german continue his flight like you wasn't there. They should make turns, try to dive, etc...or even try to shoot you down!