What software/hardware are you using to calibrate the displays? By 'calibrate' you mean colour calibration, correct?
If so, you need to calibrate each display independantly, because each physical panel will vary slightly (despite being the same model). This will be your first challenge. You need a video card that can handle multiple Look-Up Tables (LUTS) and calibration software/hardware that can manage more than just 1 calibrated display.
At home, my Datacolor Spyder3 Express can only manage 1 calibrated display. I will need to confirm, but I am quite certain the Radeon HD Series products do not have the ability to handle more than 1 LUT too.
The next challenge will be that creating the Eyefinity Group will make the system think you just have 1 big display connected, so I am concerned it the 3 independant calibrations (if you get them going) will go bonkers and simply won't work as you wish.
AMD Customer Care
The information presented in this document is for informational purposes only and may contain technical inaccuracies, omissions and typographical errors. Links to third party sites are for convenience only, and no endorsement is implied.