The isothermal Brownian-type molecular dynamics simulation was applied to study the melting scenario of noble-metal-based bimetallic clusters. The failure of the simulation results to portend a compatible melting temperature, T_melt, which is defined in the specific heat C_V at its principal peak and in the Lindermann-like parameter at the temperature which it exhibits drastic change, has prompted us to calculate the velocity autocorrelation function VACF or its Fourier-transform, the power spectrum as another useful variable for describing cluster melting. Two bimetallic clusters, namely Ag₁₃Au₁ and Ag₁₃Cu₁, were selected for illustration. We effected comparative studies of the thermal and dynamic properties of the Ag₁₃Au₁, Ag₁₃Cu₁ and Ag₁₄ and explored isothermally the VACF and spectral density of individual atoms in each of these clusters as well as the corresponding whole cluster. We examined, in particular, the influence of the impurity atoms Au and Cu. It is observed that the C_V of Ag₁₄ displays a prepeak which is absent in Ag₁₃Au₁ and Ag₁₃Cu₁. The physical origin of this prepeak feature was studied and its presence is ascribed to the migrational relocation of the adatom in the cluster. From the temperature change of VACF and spectral density, we deduced T_melt. It is found that the calculated T_melt inferred from VACF and power spectrum agrees quite well with that determined from the main peak position of C_V. [DOI: 10.1380/ejssnt.2009.149]