Why do pixhawk boards use both the MPU600 and the L3GD20?

I am trying to gather gyro data from Qgroundcontrol for a project and noticed that the attitude roll, pitch, yaw, rollspeed, pitchspeed, and yawspeed were processed through the MPU6000.

If this is true what is the point of integrating the LG3D20 if the MPU6000 sensor does all the work?