Dynamics of poly(vinyl alcohol) (PVA) hydrogels having chemical and physical transient cross-links simultaneously (dual cross-link PVA gels) were studied by microrheology based on diffusing wave spectroscopy (DWS), classical rheology and single dynamic light scattering (DLS), and compared with those of corresponding chemical and physical PVA gels. Three different relaxation modes (fast, intermediate and slow modes) are observed for physical gels, while one mode (fast mode) is found for chemical gels, and two (fast and intermediate) for dual cross-link gels. The three modes are attributed respectively to Brownian diffusion of PVA polymer or collective diffusion of the network or gel mode (fast mode), macroscopic stress relaxation (intermediate mode whose characteristic time shows q(0) dependence) and Brownian diffusion of aggregates (slow mode). Microrheological measurements are in good agreement with macrorheological showing segmental Rouse mode dynamics in the high frequency range. For physical gels, we found Maxwell type viscoelasticity characterized by a crossover frequency (maximum of G '') and G' similar to omega(2) and G '' similar to omega(1) in the lower frequency range. The chemical gels displayed an elastic plateau with low G '' at low frequency. For the dual cross-link gel a maximum of G '' was observed, and its characteristic time agrees with that of the intermediate mode measured by DLS. We show that this relaxation mode corresponds to the associative Rouse mode characterized by G' = G '' similar to omega(0.5), depending on the dissociation rate of the reversible transient cross links We propose a stress relaxation mechanism of the PVA chains in the presence of elastically inactive but associative transient cross links which induces incomplete stress relaxation.