Sky generally do quad, not twin LNBs. The golden rule is that the tuner must match what is connected to it.
So if your hardware is as follows:-
Wire from 28.2 LNB direct to tuner A, (no splitters in betweeen)
Wire from 28.2 LNB direct to tuner B, (no splitters in betweeen)
Tuner config should be:
Tuner A: Simple, single, 28.2
Tuner B: Simple, single, 28.2
