Calibration will maximize the color performance and accuracy of a display for a particular workflow (like photography, videography, etc.). Not all displays perform identically, use identical backlight technology or age identically. When you see displays next to each other they can be perceived a different. If you perceive a difference in your displays this does not mean that something is wrong.

Using the Spyder X2 software (Ultra and Elite), you can use the StudioMatch and SpyderTune functions to match / align you monitors.