doublesim.launch

<launch>
<node
pkg="turtlesim"
type="turtlesim_node"
name="turtlesim_node"
ns="sim1"
/>
<node 
   pkg="turtlesim"
   type="turtle_teleop_key"
   name="teleop_key"
   required="true"
   launch-prefix="xterm -e"
   ns="sim1"
/>
<node 
   name="turtlesim_node"
   pkg="turtlesim"
   type="turtlesim_node"
   ns="sim2"
/>
<node
   pkg="agitr"
   type="pubvel"
   name="velocity_publisher"
   ns="sim2"
/>
</launch>