A 1D drift-diffusion model is used to study atmospheric-pressure dual-frequency (DF) dielectric barrier discharges in argon using the plasma modeling platform PLASIMO. The simulation exhibits an excellent agreement with the experimental results and gives insight into the DF plasma dynamics e.g. the electric field, sheath edge profiles, ionization/excitation rate and electron energy distribution function (EEDF) profiles. The results indicate that due to the radio-frequency oscillation, the electric field, sheath edge and thus the ionization/excitation are temporally modulated. As a result, the plasma conductivity is enhanced as the plasma density is higher. The discharge development is slowed down with a lower current amplitude and a longer duration. The time-averaged sheath is getting thinner with a more pronounced ionization rate and a longer contacting time near the substrate, which could help to improve the efficiency of plasma-assisted surface processing. In addition, the DF excitation exhibits a capability of modifying the EEDF profiles and controlling the plasma chemical kinetics, which can be applied to other relevant fields e.g. gas-phase chemical conversion.