I dont know where you are, but in Australia it is only specified as 'coupled' not the 'dual coupled' you mention.There’s a Hyundai patent for the ‘Dual coupled torsion beam axle’ here:
US8505939B2 - Coupled torsion beam axle - Google Patents
A coupled torsion beam axle (CTBA) has improved compliance characteristics that can control a toe value of a rear wheel to be towed in during steering when the steering is performed in a simple structure. The CTBA includes trailing arms and carriers on which rear wheels are mounted via carrier...patents.google.com
The ‘Dual’ system has tie rods connected to the rear wheel carriers and anchored at the centre of the axle. This allows toe in and out dependant on suspension movement.
A ‘Top Gear’ road test mentions that the axle is ‘coupled’ to give semi indépendance and Hyundai advertises the i20N ‘Dual’ axle but both are clearly is untrue!