Now I have the official statement from Tesla: The mobile connector is 16A only for 3 phases:
11 kW fähiger Universal Mobile Connector, IEC 60309 5 Pin Rot 16A/3-Phase (400 V), oder IEC 60309 3 Pin Blau 32A/Einphasig (240 V) Adapter
So in Germany, you are actually better off with 230V/32A (IEC 60309 3 Pin Blau 32A/Einphasig) giving you 7,36 instead of only 6,4kW. And you don't need a dual charger for that.
The only way to benefit from a dual charger would be if you get either from Tesla a HPC (not available for Germany and I doubt it ever will be because it would have to be very different from the US one with our "Drehstrom" input) or from a vendor like Mennekes a home charger and Type2, 400V 3p+N+PE PP + CP cable that is stationary.
As long as Tesla doesn't offer a 32A / 3 phase mobile connector, on the road 400V/32A outlets just won't give you more than 6,4kW. You can only charge at 12,8kW if a charging station has a build in Type2 plug terminated cable.
That is not what you expect from a 100k€ car with supposedly 22kW dual chargers on board. I hope Tesla learns more about power supply in Germany soon and this stupid issue goes away before my MS is delivered in December.