kicker l7 15's box

In most cases yes. Kicker actually recommends it that way as well. I also always try to do it that way. If for some reason one sub blows it will help protect the other by it still being and operating in a correct enclosure. Usually the only way i run more then one in a single chamber is if im dealing with space restraints because the sub will act as if it is in a little bit larger enclosure. Also output and sound quality are generally better in seperate chambers.