This is soo odd- I noticed that the difference in look changes depending on which screen is set to the main display! Both have the exact same settings and I did the reset as you suggested!Make sure both displays are set to the same profile, too. You can have them on different color profiles and that will obviously make things look different, although I assume you've already eliminated this as an issue.
Or maybe this is something that has only to do with the screensaver? Like apple tuned them to not look identical if you have two screens side by side? I have no real other way to test this properly..