This work proposes a new method for dissociating both channel conductions of two levels vertically stacked inversion mode nanowires (NWs) composed by a Gate-All-Around (GAA) level on top of an Q-gate level. The proposed methodology is based on experimental measurements of the total drain current (I-DS) varying the back gate bias (V-B), aiming the extraction of carriers' mobility of each level separately. The methodology consists of three main steps and accounts for V-B influence on mobility. The behavior of non-stacked Omega-gate NWs are also discussed varying V-B through experimental measurements and tridimensional numerical simulations in order to sustain proposed expressions of mobility dependence on V-B for the bottom level of the stacked structure. Lower mobility was obtained for GAA in comparison to Omega-gate. The procedure was validated for a wide range of V-B and up to 150 degrees C. Similar temperature dependence of mobility was observed for both Omega-gate and GAA levels.