your wiring is completely wrong!
I cant even follow it, but at a guess, you have one sub wired up bridged, and the other sub wired...
wait, thats not it either... maybe I'll draw a pic :s lol
edit: ok, at a guess, one sub is wired up to the right channel, the other sub, is wired up to the positives of both channels, and is therefore, doing pretty much nothing. lol
but, it is also getting power from through the other sub... lol
your best option, is to either run one sub per channel, or disconnect the wires wrapped in black tape, from teh amp... unless they aren't even connected? and then its all good!! lol