If a controller is in the 'backup-master' or 'backup' role, it will not terminate any APs. Once it's role changes to 'Master' (assuming the primary master failed), then it will begin terminating APs.
If you have two separate standalone master controllers, where they are both in the 'master' role and you are terminating APs on both and manually syncing the config (or using AirWave), then both masters would be able to termiate APs.