Actually, I don't think it's possible because two identical PMD sensors will have the same I2C ids and communication will interfere. All cameras, with the exception of right stereo (if stereo flex is used) are communicating on the same (primary) i2c bus. The right stereo camera uses the secondary i2c bus. If it were possible to change the I2C id of the PMD sensor, then it could work, but I am not sure if that's an option.