I think that all monitors have different behaviour, and to some degree vary with time.
I dont think that the same can be said for OS and video drivers? Sure, there are quirks with how they load LUT (or delete them) etc, but are you saying that my colors change if I go from Nvidia to ATI graphics?
Yeah, OS and Drivers by themselves do not vary over time or copy to copy. They are software, so they are (generally) consistent. What I meant to say is that even using the same video card on different machines, if you are using Mac vs. PC vs. Linux, they look different because they use different gamma settings. That is what I meant by OS. Also as we know some video cards (and the driver/OS combination) can support more colors and better gradients than others.
As noted by others however, if it is DVI to DVI connection comparison, you SHOULD see it identical. My past experience of noticing difference came from using multiple machines with different video cards sharing the same monitor using VGA analog connectors via a KVM. In that case, the color was very slightly different from card to card due to the tolerance range. This is probably no longer true on a full digital connections (so ATI and nVidia should display the same assuming using full digital connectors).
BTW, in this case, I wonder if going through the docking station is also making the color difference greater? It is another analog connector that degrades the signal. I wonder if hooking up the cable directly to the laptop would reduce the color difference?