I cant see how that would be the case as cable works a different way to satellite, you are not limited by the 13v/18v V & H polarity issue that you have with satellite, you should be able to decode several channels at the same time. As this is clearly going down the route of fraudulently obtaining Virgin Cable services that's where my involvement ends.
I would suggest that you ask help with this issue from a forum which doesn't include cardsharing in its rules.