I have never seen exactly what you have described in a 480V application. If the relays are the same part number, the coil voltage should be roughly equally divided and neither will likely pick.
Here is a setup that you will often encounter:
A 480V to 120V control transformer will be powered from, let's say, phase A & phase B. Two 480V coil relays will be connected between A & C, and B & C, in order to check for phase loss. The NOHC (normally open held closed)"a" contacts of the two relays are placed in series to disable the control ladder should you lose a phase.
This method does NOT protect you from phase reversals or offer tight voltage tolerances. Phase loss monitors are more commonly used for this purpose in the present day.
Joe
