The influence of the spacer thickness upon the apparent mobility and the efficiency of electron transfer between two closely spaced quantum wells has been measured. By decreasing the distance of the delta-doped layer from the InGaAs channel below 100 angstrom, the efficiency of charge transfer into the InGaAs channel is increased. A dramatic drop is observed in the apparent mobility of the structure with the GaAs embedment when that distance is 50 angstrom. This indicates that the experimentally measured electron transport properties must be considered in terms of the parameters of two interacting channels, and are dominated by the properties of the embedded GaAs.