Hardness of and stress in tungsten carbide-diamond like carbon (WC-DLC) multilayer coatings sputtered in reactive argon/acetylene plasma have been studied as a function of the bilayer thickness. The multilayer structure has been deposited by a periodic modulation of the reactive acetylene gas flow from 0 to 5 sccm, producing a series of pure WC layer and W-C:H amorphous layer. Internal stress and microstructure have been investigated by wafer curvature and transmission electron microscopy whereas hardness was obtained by nanoindentation. In a previous paper on WC-DLC multilayers [Appl. Phys. Letts. 90, 021913 (2007)] we reported an interface stress of 11.12 N/m. By changing the layout of the gas lines in the deposition equipment, a new series of multilayers were produced. Our results show that in this new series of multilayers, the compressive stress exhibits the same dependence on bilayer thickness as reported before and a huge interface stress of 8.5 N/m is still present in the multilayer. In this new series of multilayers, we are reporting a hardness of 18.7 GPa, and contrarily to the observed in the first set of WC-DLC multilayers, the hardness does not depend on the bilayer thickness. These results are discussed in terms of the microstructure of the individual layers and the structure of the interfaces.