Solved.
Ensure you have followed the instructions here: http://www.hauppauge.com/site/support/linux.html and are running a supported version of Ubuntu and Kernel. I had to change kernel version back to 4.4 to get it to work. I now see both tuners.
From Hauppauge support:
supported kernel versions:
Ubuntu 16.04.1 with kernel 4.4
Ubuntu 16.10 with Kernel 4.8
Ubuntu 17.04 with kernel 4.10
Not supported Ubuntu 16.04.2 to 16.04.4 because they are based of kernel 4.4 but load 4.8 hwe which is not really 4.8 kernel.
You then need to ensure you have the demodulation firmware installed (European/AU/NZ only I believe) https://forums.plex.tv/discussion/comment/1459572
Download demoduldation firmware from http://palosaari.fi/linux/v4l-dvb/firmware/Si2168/Si2168-B40/ - I’m using 4.0.25 and it’s working great. Place into /lib/firmware
