The only benefit is when your ships start taking damage on its components. If you have 2 ecm's then you will still have the bonus when only one is damaged. I think this is the way it works, but not sure.

<t> Some of my planets and stations show that there are "[none]" ships docked and several ships waiting. The most I've seen are "Docked: [none] 126 waiting". After looking around a bit I found that in the list over ships waiting to dock the top ship is always a military ship, my own race and other ...