-D num, --device=num Use only the given DVB device (num = 0, 1, 2...). There may be several -D options (by default all DVB devices will be used).

The way I first read that, to make it use device 1 and 2 and not 3, you would use: -D 1, 2 or: -D 1,2

But it seems you can't put more then one per "-D". You have to use: -D 1 -D 2