Comparison of continuum light curves emitted by BBH systems when both the BHs are active, with q_L = 1 : 1, i_obs = 60°, q_M = 0.1 (left column) and 0.5 (right column). The top panel shows the observed continuum light curve contributed by Doppler Boosting effect from the two co-rotating black holes. The Doppler boosted or weakened flux modulated by the secondary and the primary BHs are shown in the middle and bottom panels, respectively. The lines in different shapes and colors are the same as in Fig. 2.