To improve the efficiency of multi-material additive manufacturing and enhance the safety of multi-robot cooperative printing with uncertain execution delay, a dual-robot cooperative path planning method is proposed for the layer-by-layer printing mode. In the proposed algorithm, the description of the printing region is reconstructed by simply using the rectangular envelope region and two-dimensional directed line segment, and the adjacency list of the printing region is established to guide the optimization direction. Therefore, redundant information about the printing region is effectively removed, which is conducive to the optimization of the problem. A multi-round cooperation strategy with multiple synchronous starting points is proposed to accommodate uncertain execution delays by separating the space of the dual-robot printing area, so as to avoid the potential collision risk of dual-robot. To further optimize the printing efficiency, local strategies are used to reduce the makespan. Hence, a better printing order can be obtained, and states of cooperative and non-cooperative printing processes can be unified. In addition, the corresponding NC control strategy is designed for the industrial application of the cooperative strategy. The simulation result shows that this method can effectively reduce the makespan of dual-robot cooperative additive manufacturing, and accommodate the uncertain execution delay of the dual-robot.