multi_robot_map_merge not merging with known init positions

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Hello! I am running 2 turtlebot3s with ros kinetic. I have them autonomously mapping under namespaces with explore_lite and I am trying to merge the maps with link text . We are trying to run map_merge with known initial positions, because the map merging algorithm with unknown initial positions does not work very well. However, instead of having one map, we are ending up with 2 separate maps in map_merge's rviz instance. Any ideas on how to get these maps to stay merged? I am starting the robots about 1 foot away, next to each other, so I am setting the params like so:

<launch>
    <group ns="/bot1/map_merge">
        <param name="init_pose_x" value="0.0"/>
        <param name="init_pose_y" value="0.0"/>
        <param name="init_pose_z" value="0.0"/>
        <param name="init_pose_yaw" value="0.0"/>
    </group>    
<group ns="/bot2/map_merge">
            <param name="init_pose_x" value="0.0"/>
            <param name="init_pose_y" value="0.3"/>
            <param name="init_pose_z" value="0.0"/>
            <param name="init_pose_yaw" value="0.0"/>
        </group>
    </launch>

and here's the map_merge launch file:

<launch>
<group ns="map_merge">
 <node pkg="multirobot_map_merge" type="map_merge" respawn="false" name="map_merge" output="screen">
   <param name="robot_map_topic" value="map"/>
   <param name="robot_namespace" value=""/>
   <param name="merged_map_topic" value="map"/>
   <param name="world_frame" value="world"/>
   <param name="known_init_poses" value="true"/>
   <param name="merging_rate" value="0.5"/>
   <param name="discovery_rate" value="0.05"/>
   <param name="estimation_rate" value="0.5"/>
   <param name="estimation_confidence" value="0.6"/>
 </node>
</group>
</launch>