Impressive list of aces downed by two-seaters.
Here are some more.
Max Ritter von Muller
Max Immelmann's death was credited to a two-seater crew, though I personally believe he shot off his own propellor after his synch gear malfunctioned.
Hans Bethge
Hans Pippart (his death is usually accredited to a Breguet 14 - that is a two-seater right?)
Walter Gottsch (his 20th victim's return fire killed him)
These men accounted for 113 machines/balloons. Distinguished as they are, a two-seater is not something to be taken lightly.
Kind reagrds,
Reinout