Endoscopic Submucosal Dissection (ESD) is an effective minimally invasive approach to removing colon cancer, yet it is underutilized, since it is challenging to learn and perform. To promote the adoption of ESD by making it easier, we propose a system in which two small, flexible robotic manipulators are delivered through a colonoscope. Our system differs from prior robotic systems aimed at this application in that our manipulators are small enough to fit through a clinically used colonoscope. By not re-engineering the colonoscope, we maintain overall system diameter at the current clinical gold standard, and streamline the path to eventual clinical deployment. Our concentric push-pull robot (CPPR) manipulators offer dexterity and simultaneously provide a conduit for grasper or cutting tool deployment. Each manipulator in our system consists of two push-pull tube pairs, and we describe how they are actuated. We describe for the first time our approach to compensating for undesirable CPPR tip motion induced by differences in the tubes' transmission stiffness. We also evaluate the workspace of the manipulators and demonstrate teleoperation in a point-touching experiment. Lastly, we demonstrate the ability of the system to resect tissue via ex vivo animal experiments.