We numerically investigate frequency-comb generation in an electrically pumped vertical-cavity surface-emitting laser coupled to two mechanical modes of a suspended mirror. Displacement-dependent cavity loss and radiation-pressure feedback couple the mechanical motion to the carrier and photon densities, producing harmonics and combination-frequency components in the photon-density spectrum. Mechanical quality factors primarily control the intensity of comb lines, whereas resonance frequencies determine their spectral distribution. The initial mechanical amplitudes influence the threshold current and relative spectral intensities, with the simultaneous excitation of both modes yielding a broader set of observable components. These results establish the dependence of the calculated comb structure on mechanical dissipation, resonance frequencies, and initial conditions in an active optomechanical cavity.