I have one extra pair of speaker wires that exceeds the 8 post wall plate I'm using. If I plan on having two of the speakers on the same 'b' channel, can I put two pairs on the same binding post? Does this screw up the amplifier? Thanks.
You can double up the wires. Whether it might damage the amp is a function of the amp, switches, volume control and the speakers. No way to tell you with what you have provided as information. I would ask the store where you bought the amp.