Those two terminals on your speakers are meant for biamping. To do this you would need to remove the jumpers between the two terminals on the speaker. If you do this, then yes, both amps can be on simultaneously. In fact, they will have to be. One will be driving the bass speaker and the other will be driving the remainder.

But, hooking up both amps, even if both are not powerd up at the same time, without removing the jumper could very possibly cause expensive problems.