[bojan]

I think the problem with calibration is, it is still relative: it relies on primary colours (R-G-B) generated by each individual screen (LCD panel, backlight etc), and those could be different for different brands/manufacturers.
I am very sure that two different-brand "calibrated" screens will ALWAYS display images differently, as you noticed (unless display unit comes from the same manufacturer).
Maybe I am wrong here.. but I never saw two different brand monitors displaying the same image in the same way. there was always a difference, sometimes huge.