Looks like I'm talking to myself in this thread...
Anyway, I did some more testing with Graphedit. It's possible to connect the BDA Source Filter of Card2 to the BDA Reveiver Component of Card1. One could arguee if this a driver bug or driver feature.
If we looking at the TV server, when the correct BDA Source Filter is found, all BDA Receiver Comonents are received and tested in the received order. This will cause BDA Source Filter of Card2 to be connected to the BDA Receiver Component of Card1. The graph will be ok, but it will not work.
So I changed some parts of the graphbuilding in the file TVCardDvbBase.cs. The algorithm no first checks if a BDA Receiver Component on the same device as the BDA Source Filter can be found.
This fixed my problems
The files are based on SVN Rev20227. Perhaps the expertise can take a closer look at this.