4 channel audio output, but i only want 2

I try to do a edit-to-tape from a SD sequence with a Blackmagic decklink extreme (SD) on a mac pro. I've connected a dvw-a500, and i'm outputting through SDI with FCP 6.0.4. The blackmagic is connected with SDI and the rs-422 controller. Everything works fine, the ETT works, but with 4 audio tracks, and i only want 2!

The strange thing is i tried all the settings within fcp for 2 channel output, But on de a500 i still see 4 channels peaking, anyone has an idea? Can it be a setting on the a500? (ref is to input video already)