How do you run multiple hector_quadrotors without separate urdf files?

edit

I'm currently trying to launch multiple hector_quadrotors with a single roslaunch command with ros-hydro. I have got it "working", I have two drones that hover and listen to different 'cmd_vel's.

But to get this to work I had to make my own versions of: aw_quadrotor.urdf.xacro
aw_quadrotor_base.urdf.xacro
aw_quadrotor_plugins.gazebo.xacro
aw_quadrotor_sensors.gazebo.xacro
aw_quadrotor_simple_controller.gazebo.xacro

And one of these for each drone.
drone0_aw_quadrotor.gazebo.xacro
drone1_aw_quadrotor.gazebo.xacro

When I look at I see that some of the commits it looks like hector_quadrotor should support multiple drones without having to edit all the urdf files.
https://github.com/tu-darmstadt-ros-pkg/hector_quadrotor/commits/hydro-devel

What am I missing? How can I make sure the plugins for gazebo don't confuse drones with the same base_link name with each other? Using namespaces doesn't seem to propagate down into the xacro macros/gazebo plugins.

My files currently look like this.

aw_spawn_two_drones_gazebo.launch

<launch>
  <param name="/use_sim_time" value="true"/>

  <include file="$(find gazebo_ros)/launch/empty_world.launch">
  </include>

  <group ns="drone0">
    <include file="$(find aw_hector_quadrotor)/launch/spawn_quadrotor.launch">
      <arg name="name" value="drone0"/>
      <arg name="pos_x" value="0.2"/>
      <arg name="namespace_arg" value="drone0"/>
    </include>
  </group>

  <group ns="drone1">
    <include file="$(find aw_hector_quadrotor)/launch/spawn_quadrotor.launch">
      <arg name="name" value="drone1"/>
      <arg name="pos_x" value="2.0"/>
      <arg name="namespace_arg" value="drone1"/>
    </include>
  </group>
</launch>

spawn_quadrotor.launch

<launch>
  <!-- push robot_description to factory and spawn robot in gazebo -->
  <arg name="name" default="quadrotor"/>
  <arg name="pos_x" default="0.0"/>
  <arg name="pos_y" default="0.0"/>
  <arg name="pos_z" default="0.5"/>
  <arg name="namespace_arg" default=""/>

  <arg name="model" default="$(find aw_hector_quadrotor)/urdf/$(arg namespace_arg)_aw_quadrotor.gazebo.xacro"/>
  <!-- send the robot XML to param server -->
  <param name="robot_description" command="$(find xacro)/xacro.py '$(arg model)'" />
  <param name="tf_prefix" value="$(arg namespace_arg)" />
  <node name="spawn_robot" pkg="gazebo_ros" type="spawn_model"
        args="-param robot_description
              -urdf
              -x $(arg pos_x)
              -y $(arg pos_y)
              -z $(arg pos_z)
              -model $(arg name)"
        respawn="false" output="screen">
  </node>
</launch>

drone0_aw_quadrotor.gazebo.xacro

<robot name="quadrotor" xmlns:xacro="http://ros.org/wiki/xacro">
  <xacro:include filename="$(find aw_hector_quadrotor)/urdf/aw_quadrotor.urdf.xacro" />
  <xacro:include filename="$(find aw_hector_quadrotor)/urdf/aw_quadrotor_plugins.gazebo.xacro" />

  <!-- Instantiate quadrotor_base_macro once (has no parameters atm) -->
  <xacro:quadrotor_base_macro prefix="drone0"/>
  <xacro:quadrotor_sensors_gazebo prefix="drone0"/>
  <xacro:quadrotor_sensors/>
  <xacro:quadrotor_simple_controller prefix="drone0" state_topic="ground_truth/state" imu_topic="raw_imu"/>
</robot>

aw_quadrotor_base.urdf.xacro

<robot xmlns:xacro="http://ros.org/wiki/xacro">
  <xacro:include filename="$(find aw_hector_quadrotor)/urdf/sonar_sensor.urdf.xacro" />
  <xacro:property name="pi" value="3.1415926535897931" />

  <!-- Main quadrotor link -->
  <xacro:macro name="quadrotor_base_macro" params="prefix" >
    <link name="${prefix}/base_link">
      <inertial>
        <mass value="1.477" />
        <origin xyz="0 0 0" />
        <inertia ixx="0.01152" ixy="0.0" ixz="0.0" iyy="0.01152" iyz="0.0" izz="0.0218" />
      </inertial>

      <visual>
        <origin xyz="0 0 0" rpy="0 0 0" />
        <geometry>
          <mesh filename="package://hector_quadrotor_description/meshes/quadrotor/quadrotor_base.dae"/>
        </geometry>
      </visual>

      <collision>
        <origin xyz="0 0 0" rpy="0 0 0" />
        <geometry>
          <mesh filename="package://hector_quadrotor_description/meshes/quadrotor/quadrotor_base.stl"/>
        </geometry>
      </collision>
    </link ...