Your question makes me think, which can be a dangerous thing. However -- Are you trying to supply HD signals to more than one HD receiver? You don't say that but I don't see a reason why more than one wire would be a possibility unless you are trying to go to more than one receiver.
A good answer is easier with a clear question giving the make and model of everything. "The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
