Turtlebot3_Fake.rviz superpositioning under odom

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Hi Team,

I ran Turtlebot3_Fake.rviz .It seems 2 robot appears at same time but it's switching position. This happens when i execute Gazebo turlebot3_world.launch. Another thing is that if i execute the roslaunch turtlebot3_fake.launch, the robot (burger) appears to be empty and TF throws "no tf data. actual error: fixed frame [odom] does not exist" . Does this has to do with missing or corrupted installation?