About each monitor, you didn't say:
- How they were connected. I.e. were you using the same, DVI or VGA cable, for BOTH monitors? (btw, if you used a VGA cable with a DVI-VGA adapter, it'll still be VGA)
- How far apart the purchases were. I.e. you can expect some degradation of the 1st monitor over an extended period of time. Plus, the 'newer' monitor, though being exactly the same model, might have come equipped with better technology/improvements.
I find connecting my monitor via a DVI cable+input makes things brighter, with increased contrast than via a VGA cable/input. G