Avoid resonances in plasterboard with absorber??

As you can read in this thread: http://www.johnlsayers.com/phpBB2/viewtopic.php?t=4299 CYEAZEL advice me to add 2 layers of drywall to avoid resonances... but in the control room:

I will build a bass trap in the rear wall, isolation wall is made by 200 mm concrete block with sand/ 50mm airgap/ 40 mm rockwool 70 kg/m3 / 1x 15 mm sheetrock. If I'll put the that bass trap in this wall, there still will be resonances on this layer of drywall??

the next week we start to doble the layers of drywall in the recording room, but it's necessary to do this in the control room too??