Problem with model duplication in a gazebo world [closed]

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In our gazebo world, we are trying to duplicate an instance of a model, in this case a simple cylinder. See the simple example below, where we are calling three items: two times the cylinder and one other item. In our world file are two models, one is duplicated. In the gazebo simulation there are only two items to be seen, the cylinder and the other item. The duplication of the cylinder does not work. Amazingly | Surprisingly, the same .world file with identical model .sdf and .config files works fine on another computer with an identical 16.04/kinetic (gazebo 7.0.0) in this installation. We reinstalled gazebo (gazebo 7.16.0), however, the problem persists. Is this a known problem?

<sdf version='1.6'>
  <world name='default'>
    <physics type="ode">
     <max_step_size>0.005</max_step_size>
    </physics>
    <include>
      <uri>model://ground_plane</uri>
    </include>
    <include>
      <uri>model://sun</uri>
    </include>
    <include>
        <pose>-1 -.35 0 0 0 0</pose>
        <uri>model://turtlebot3_autorace/pumpkin</uri>
    </include>
    <include>
        <pose>0 0 0 0 0 0</pose>
        <uri>model://turtlebot3_autorace/pumpkin</uri>
    </include>
    <include>
        <pose>1 0 0 0 0 0</pose>
        <uri>model://turtlebot3_autorace/border_cylinder</uri>
    </include>
  </world>
</sdf>