Qolsys Smokes / CO Detectors

You would not need to double up. With Interconnected wired smoke detectors, you can use this 319.5Mhz FireFighter Audio Detector

You only need one to be mounted within 6" of one of the interconnected smokes to monitor all of them. The device listens for the smoke detector’s cadence and when it hears that it sends the signal to the alarm panel.