I have an electrically operated hydraulic valve. It has 2 solenoid on each end and is self centering when all elecricity is removed.

During normal operation the solenoid on one side is energized, moving the hydraulic spool over. When electicity is removed and applied to the other solenoid, the spool moves in the other direction.

My question is, If electricity were applied to both solenoids simultainiously (due to malfunctioning or incorrectly setup equipment), would it cause coil burn out? If it does, why does it? Does it overheat due to the iron core not being pulled into the center of the coil?
We had this senorio happen where due to setup error both coils were energized at he same time and after a short period of time one of the coils failed. However before the coil failed, the valve "seemed" to operate as normal except it would never stay in neutral. Apparently the one coil was stronger then the other and over rode the weaker one.

Does anyone have any insight on this?

If the core is already at one end of the travel, (one coil energized) and the other coil is then energized, the second coil will not have enough force to pull the core to center. The force from a solenoid is a function of core position, with maximum force available at the end of travel.

So the core will remain at one end of travel, and the other coil will overheat due to excessive current (caused by the core not moving to complete the magnetic circuit).

An enregized solenoid coil will burn up with out at least a partial presents of the core. I believe you were correct about what happened. When one coil finally gave up the smoke the other got the core The surviving coil is probablly degraded and could have a shortend life expectancy. If this is a safety item I would replace them both.
I've seen coils removed from the assembly to change the core/shuttle (which is a high fail mechanical part) and during this time the plant energized the coil. Naturally when everything was put back together it didn't work because the coil was fried.

Thanks for the replies.
That confirms my suspicions!