Several mixed cation effects in the electrical conductivity and mechanical loss spectra of mixed alkali and mixed alkali-alkaline earth glasses are identified, and their interrelation is analyzed. Apart from the classical mixed cation effects in the ionic diffusivities, we find characteristic effects in the frequency response of the complex electrical conductivity and in the magnitudes of mechanical loss peaks. We observe that the latter two effects are the more pronounced, the less the diffusivities of the faster and the slower ions differ. This suggests that these two mixed cation effects are fingerprints of an incomplete decoupling between the transport of the faster and the slower ions.