Any suggestions and recommendations for mapping long straight corridors using gmapping?

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Hi,

I am trying to map a long straight corridor using turtlebot gmapping demo on actual robot. For a short segment of the run the robot maps the corridors nicely giving straight edges but as the distance increases, i find it hard to map the environment correctly. Either it curves out the corridor or it branch out another map out on the rviz suggesting it is not able to localize properly. I get parallel maps where the corridor branches out from the main map.

Any suggestions into improving the map? What settings are recommended. My turtlebot is properly calibrated , i know there are imu errors and odometry errors involved but how to improve on it? Does changing the topic to /odom provide better results?

I am using ROS fuerte with kinect.