Zing! Yeah don't worry about colors. Really though my hunch is you have something acting up on your DK video board. I haven't seen a monitor trip out and double everything up, it would have to screw up all three video signals basically to do that, and I don't think that's what's up.
If the image is shaking and fluttering and acting crazy, it's possible the sync could be wayyyy off, but my money's on the video output from the DK pcb.