Many communication signals exhibit cyclostation-arity with some cycle frequencies and the cycle frequencies are related to signal parameters such as symbol rates, carrier frequencies. Dandawate proposed a statistical test to check the presence of cyclostationarity using a single cycle frequency. And recently, the statistical test has been applied to spectrum sensing. For most modulated communication signals like BPSK and QPSK, the (conjugate) cyclic autocorrelations at positive and negative cycle frequencies are conjugated. In practical wireless environment, the (conjugate) cyclic autocorrelations at positive and negative cycle frequencies are affected by noise and multipath fading differently, and this property could be used to improve the performance of spectrum sensing. In this paper, we analyze the cyclic autocorrelations at dual cycle frequencies in multipath fading model and extend Dandawate's test to dual cycle frequencies for spectrum sensing. We show that the proposed dual cycle sensing scheme can achieve frequency diversity effect. The simulation results demonstrate that the proposed scheme performs much better than single cycle detector.