Not sure if I interpret your question correctly, but my understanding is that you need to 'calibrate' the TV first before doing anything with the Duo. This will insure minimal manipulation of the signal from the DUO and insure that you remain within your diplay's physical capabilities.
I'm including a pre/post duo calibration of my Panasonic G25 (sorry about the poor picture quality, but my crippled Calman Home licence refuses to output reports).
Without the Duo, the G25 was a lot of frustration : I spent more time trying to calibrate this set over a 1 month period than I did with previous RPTV over 10 years.
After calibration, without the Duo, I had the following problems:
Grayscale: Unmanageable inflection points at 30 and 50 IRE - too much green below 30 IRE and too much red at 50 IRE.
Gamma: well below 2.0 resulting in overly bright picture and washed out low APL scenes.
Slight but frequent posterization problems.
Frequent yellow tinge on people's face.
Notorious floating black issue that required a voluntary black crush to minimize the problem.
After Duo calibration, all issues were resolved, with the exception of floating black (which is why I aimed for a 2.3 gamma, trying to hide it).
I am very pleased with the results which are, well... spectacular...
The only problem I have with the Duo is audio wise as it does not seem to be able to buffer without introducing regular audio dropouts; but this is a minor issue since the problem is solved by setting to delay to minimum on the Duo.
PanaG25_DuoCalibration.pdf 287k . file