<p>In this research, a comparative analysis was conducted on the performance and efficiency of the dual-anchor soft robot (DASR) and the extension-contraction soft robot (ECSR). These robots were constructed by imitating the locomotion of razor clams. The penetration force for extension actuators and the anchorage force for expansion actuators in dry sand with distinct relative densities were tested by differentiating input air pressure and length-to-diameter ratios (<i>λ</i>). On the basis of the findings, a DASR and an ECSR were developed. DASR comprised two expansion actuators as the head and the tail segments at two ends, and one extension actuator as the middle segment. ECSR was composed of an extension actuator. A method based on the force equilibrium was introduced to ascertain and adjust the geometric parameters (length of each segment) of DASR. The burrowing-out performance and efficiency of DASR and ECSR in sands with distinct relative densities were explored. The results revealed that DASR exhibited high efficiency in dense sand in terms of lower time of burrowing-out, slip-to-advancement ratio, and cost of transport. ECSR might perform better in looser sand in terms of higher average burrowing-out velocity, higher advancement in each cycle, and lower energy consumption. However, it had larger slips than DASR. DASR could realize steady advancement and net displacement in each cycle and effectively decrease slips. These findings demonstrate the benefits and usability of the dual-anchor motion and offer new insights into the application of the dual-anchor mechanism in the burrowing of robots.</p>