I have problems with coding

Help! Error BCE0089: Type 'Footsteps' already has a definition for 'OnGrassSound' I can't seem to fix it.

 #pragma strict
 
 var OnGrass : boolean = false;
 var OnGrassSound : AudioClip;
 
 var OnGrassTimer : float = 0;
 var OngrassCool : float = 0.6;
 
 private var chMotor : CharacterMotor;
 private var controller : CharacterController;
 
 function Start()
 {
     chMotor = GetComponent (CharacterMotor);
     controller = GetComponent (CharacterController);
 }
 
 function Update()
 {
     if (controller.velocity.magnitude > 0 && Input.GetKey(KeyCode.LeftShift))
     {
         chMotor.movement.maxForwardSpeed = 20;
         chMotor.movement.maxSidewaysSpeed = 20;
     }
 
     else
     {
         chMotor.movement.maxForwardSpeed = 10;
         chMotor.movement.maxSidewaysSpeed = 10;
     }
 
     if (controller.velocity.magnitude > 0 && OnGrass == true)
     {
         OnGrassSound();
     }
 
     if (controller.velocity.magnitude > 0 && Input.GetKey(KeyCode.LeftShift) && OnGrass == true)
     {
         OngrassCool = 0.4;
         OnGrassSound();
     }
 
     else
     {
         OngrassCool = 0.6;
     }
 
     if(OnGrassTimer > 0)
     {
         OnGrassTimer -= Time.deltaTime;
     }
 
     if(OnGrassTimer < 0)
     {
         OnGrassTimer = 0;
     }
 
 }
 function OnGrassSound()
 {
     if(OnGrassTimer > 0)
     {
         audio.PlayOneShot (OnGrassSound);
          OnGrassTimer = OngrassCool;
     }
 }