This article briefly reviews the theory and modeling of single-surface multipactor discharge on a dielectric, focusing on recent studies on two-frequency RF-field-induced multipactor. A novel multiparticle Monte Carlo simulation model with adaptive time steps is used to investigate the time-dependent physics of multipactor discharge. Two-frequency RF operation is found to be effective in reducing multipactor strength compared with single-frequency RF operation with the same total RF power. Strong multipactor mitigation is also demonstrated for nonsinusoidal RF fields of multiple frequencies. Migration of multipactor trajectory is shown for different configurations of the two-frequency RF field. Frequency-domain analysis shows that multipactor-induced normal surface charging electric field consists of only even harmonics of the RF frequency for single-frequency RF operation, but is dominated by strong intermodulation products of the RF carrier frequencies for two-frequency RF operation.