Another trick that helps is to make sure that the two side by side monitors are using different refresh rates.
If the monitors use the same refresh rate, the unshielded electromagnetic impulses can set up an interference which is analogous to an audio beat (difference) frequency. That is, although the refresh rates are nominally the same, they will differ slightly in frequency or phase which results in an interference pattern in an adjacent monitor. Like a musical or audio beat frequency, this "new" frequency is equal to the difference between the frequencies of the adjacent monitors. Since the frequencies are almost the same, the difference can be manifested by a slowly moving line repeating over and over across the screen. Very distracting to say the least.