My screen is two-toned also. I would not care which color, as long as it was even I could calibrate it to standard color.
I have too much work to do to send it back and wait for another that could possibly be also two-toned. I have opened a case with Apple support and have an option to send it back for exchange before 1/9, or bring it in to be fixed anytime in the year. It is perfect in every other respect, so I think I will wait until I see good screens in the Apple store and then bring it in to be fixed.