Dual-anchor live streaming represents a fresh development in the e-commerce arena. Both anchors not only engage in real-time interactions with viewers but also share nonverbal communication cues among themselves. However, the impact of these nonverbal cues on sales remains a fascinating void. In our study, we initially devise metrics for dual-anchor nonverbal communication, encompassing response latency, direct gaze, facial animation, and physical distance, across both auditory and visual dimensions. Utilizing real sales pitches, consisting of video recordings and sales data, we develop econometric models to assess the influence of dual-anchor nonverbal communication on consumer purchasing behavior. We discover that these nonverbal cues significantly affect audience purchasing in an inverted U-shaped pattern. Moreover, the effect of response latency on purchase is negatively moderated by anchors' speech rate. Surprisingly, as external observers, audiences can discern the interpersonal dominance between anchors through these cues, and both exceedingly low and high levels of nonverbal dominance may reduce the anchors' persuasiveness. With well control of streamer-related confounders, our results underscore the pivotal importance of nonverbal communication between dual anchors and identify optimal levels of their nonverbal interactions, providing practical guidelines for live streaming professionals.