The things I can see:
Try ConnectedMonitor "DFP, DFP" (or "CRT, CRT")
Try changing the TwinView orientation
Make sure your metamodes match the resolution. In your case, try "1280x1024, 1280x1024; 1024x768, 1024x768"
Is the second monitor vet refresh the same as the first one?
And from what your log is saying, some options weren't set when they should:
(WW) NVIDIA(0): To enable TwinView, you must also specify:
(WW) NVIDIA(0): Option "MetaModes" "<metamode list>"