A theoretical study of the time-dependent probe response of a single electromagnetically induced transparency (EIT) window to double EIT windows is presented by numerically solving the equations of motion of the density matrix in a quasi-Λ-four-level configuration. There is a coherent transient process with high quantum beats. This effect can be explained using the dressed state formalism. The quantum beats result from quantum coherence effect between the levels driven by RF field. The results show that when the probe field is on resonance with a bare-state transition, the beat frequency is one-half of RF Rabi frequency in transient absorption response. While the probe field is on resonance with a dressed-state transition, which results from the atom system interaction with strong RF field, the beat frequency equals the RF Rabi frequency in transient absorption response.