In a multi-operator multi-robot (MOMR) teleoperation system, each human operator controls a remote slave robot via a corresponding master interface to jointly perform complex tasks. This paper provides a hardware-in-loop simulation to study collaborative haptic interaction of MOMR teleoperation systems based on decentralized control approach. This approach uses physically-based motion simulation for rendering cooperative virtual manipulation in haptic interfaces. The dynamic behavior including contact force and collision detection is calculated using Open Dynamics Engine and reflected on haptic interface to assist operators to implement cooperative tasks in graphic environment. The result of this study constitutes a significant step forward for distributed haptic collaboration.