dual density dual diagnosis dual disc dual display dual drive dual education dual effect dual element dual energy dual engine dual enrollment dual exhaust dual extruder dual filter dual flush dual focus dual form dual frequency dual front dual fuel dual function dual functionality dual functions dual gauge dual head dual identity dual income dual input dual interface dual language dual layer dual legal dual lens dual life dual line dual link dual lock dual mandate dual meaning dual mission dual mode dual monarchy dual monitor dual monitors dual mono dual motor dual national dual nationality dual nationals dual nature dual objective dual or multiple dual output dual overhead dual personality dual perspective dual phase dual pixel dual polarization dual port dual power dual pricing dual problem dual protection dual purpose dual rate dual rear dual redundant dual responsibility dual role dual roles dual screen dual screens dual sensor dual shock dual space dual speed dual stack dual stage dual standby dual strategy dual stream dual structure dual studies dual study dual system dual systems dual temperature dual therapy dual time dual tone dual track dual training dual use dual view dual vocational training dual voltage dual wall dual watch