Can I use the same map for multiple robots running move_base

edit

For some experiments, I am trying to use two ground vehicles which would share the same map. Right now I am working on my configurations using gazebo. What I am trying to do is use the move_base package and launch a node for each vehicle. the issue I am running into is the mapping of topics and parameters. If I add a namespace to the launch file, then the map topic is also remapped. For example:

<launch>
  <group ns="vehicle1">
    <node pkg="move_base" type="move_base" respawn="false" name="move_base" output="screen">
    </node>
  </group>
  <group ns="vehicle2">
    <node pkg="move_base" type="move_base" respawn="false" name="move_base" output="screen">
    </node>
  </group>
</launch>

This code will publish the maps on the topics '/vehicle1/map' and '/vehicle2/map'. How can I launch this concept where both vehicles will just use '/map'?

(This is a significantly reduced example, it currently won't actually publish a map, it is just for an idea of what I am trying to do)