I think unless the big league whose beacons are been taken are not concerned about the beacon they will take it back.. some might take it during the beacon Massacre or some might take it after it in some other event like beacon conquest.. smaller leagues can only plan it is such a way that the beacons are taken at the end of the beacon massacre so that the chances of taking back a stacked beacon is reduced, however i dont think this can be eliminated unless they have backing from another big league.