Hi Trevor
My sincere apologies you were correct the first time. My German translation let me down
However I am not sure RU are entirely correct. The following is as I understand it.
The Do C 1,was launched on July 24, 1931, but on a flight, on July 25 1931 under the designation Do C2a,, built largely according to original design but
with two floats to provide a reconnaissance version. Due to extreme shape of the wing it did not meet the performance expected
Attempts were made to improve the insufficient climbing performance. This led to introduction of an additional small lower wing
It was given the designation Do C3a and made his maiden flight on the 18th
September 1931.
You have control.