Ok the CoCoL.dll file was not present in the Duplicati 2 program folder. I got a clue from this thread:
I uninstalled 2.0.2.15 and then reinstalled it clean. Now the CoCoL.dll file is there and it starts properly.
The in-place upgrade over 2.0.2.1 to 2.0.2.15 failed to install the dll.
You guys might need to look into the installer logic a bit more.
Thanks!