  We report a detailed study of the influence of the electron-electron
interaction on physical observables (conductance, etc.) of a disordered
electron liquid in double quantum well heterostructure. We find that even in
the case of common elastic scattering off electrons in both quantum wells, the
asymmetry in the electron-electron interaction across and within quantum wells
decouples them at low temperatures. Our results are in quantitative agreement
with recent transport experiments on the gated double quantum well
Al$_x$Ga$_{1-x}$As/GaAs/Al$_x$Ga$_{1-x}$As heterostructures.
