enorbet, where do you see 2 sets of video chips on the output op provided so far?
i don't.
wheet, i don't know how you got on with el barto's suggestions; anyhow, now that your pci-ids are fixed, we need that output again:
Code:
lspci -k | grep -iEA5 'vga|3d'
to assess your situation.
but i already have a fairly strong suspicion that you just need to install the proper proprietary (sic) driver for this GeForce GTX 960. and make sure X sees it, and nouveau is blacklisted and such. but all that should be explained on the debian wiki.