Otto Bertram's brothers

[bakerman]

Source http://luftwaffe.cz/bertram.html :
"Otto was one of three brothers serving in the Luftwaffe, two of whom had been killed in action – Hans, Gruppen Adjutant of I./JG 27, had been shot down over England in September 1940, and Karl, a nightfighter pilot with 9./NJG 1, had been killed when he crashed his Bf 110 west of Kiel following an engagement with a RAF bomber on 28 October. Otto, as the sole surviving brother was prohibited from further combat duty."

But at the Invalidenfriedhof cemetary in Berlin is a memorial stone with these two names:
-Oblt. Hans H. Bertram +30.9.40 London, Adjutant einer Jagdgruppe
-Lt. Kurt Bertram +11.8.40 Themse-Mündung.

Which one is right as the second brother? My guess is Kurt.