No - the reason being the card is representing the DVB-S tuner as one input and the DVB-C/T input as another, both independent of each other. TVHeadend allows you to restrict the number of streams per input (so you can limit the number of streams on the DVB-S or DVB-C/T input, but not link them together so if one is active, the other can't be etc.)
This sounds like a driver issue because presenting two inputs logically suggests two available tuners, if both cannot work simultaneously then something is wrong at the hardware/driver level.