Hi Thanks for the quick response,
I have actually connected the tuners together to the same feed with a splitter (exactly the same as having either an internal or external loop), the danger is that I can't set it to loopthrough so I have to make sure if I set a recording I either watch or record something on the second tuner which is on the same polarisation and frequency so as to not risk putting different voltages from two tuners in to the same cable.
Currently tuner 2 is set to equal to tuner A