Assuming you are using a universal LNB when you have two inputs connected to the same feed they will only be able to tune to the same group of channels.
To access both polarisations and bands (Horizontal and Vertical; Low band and High Band) an LNB will operate in four discrete modes - this means that for PVR applications you ideally need a feed per tuner - and that a single LNB can only provide access to around 1/4 of the available channels at once.
If you use a passive splitter you will find that one of the following happens
1) A tuner connected to one output always wins
2) 22Hz switching being on (i.e. Highband) always wins, polarisation from one output always wins
3) Horizontal polarisation being selected always wins, 22Hz switch from one output always wins
4) Horizontal polarisation and High Band win
5) When output one is active that wins, and output two gets nothing
1, 4, and 5 are the most likely outcomes
Assuming you are using Astra at 19.2'E try tuning to
11.479V - TV Monde on tuner 1
11.509V - Montanggne TV on tuner 2
If any of 1 - 4 are yours then both of these should be viewable.
Basically you can tune to one, and only one, of the following four groups of channels at once:-
Lo Band Vertical - 10.700 - 11.700 Vert - 22Hz OFF, 13V
Lo Band Horizontal - 10.700 - 11.700 Horiz - 22Hz OFF, 18V
Hi Band Vertical - 11.700 - 12.750 Vert - 22Hz ON, 13V
Hi Band Horizontal - 11.700 - 12.750 Horiz - 22Hz ON, 18V
For a PVR application this would obviously be rather unpredictable!
(It would be neat if you could specify in TV Headend "Tuner B can only tune to the same band / pol as Tuner A" to allow the flexibility in recording when you have a single feed while leaving it semi-predictable - i.e. a recording doesn't die half way through)
