thanks for your ideas, but unfortunately it does not help.
The module which carries the BMA020 has a level shifter.
I have no external pull-ups (I know they are included on DUE).
I use several other I2C chips single and combined on the DUE.
What's not clear to me, why helps the oszi probe?
Now I use a 33pF SCL to GND. And it works. 