problem with arcade racer timer system

hey all, I'm in the process of modifying the lap and checkpoint system I have in my arcade racer into a timer system, however I'm having issues where once I enter the second checkpoint it gives me double amounts of the bonus time (e.g. instead of 30 seconds the second checkpoint gives me 60 seconds) and when I pass the finish checkpoint it doesn't trigger the function at all. I'm not sure where in my script I would call out the AddTime function. Any thoughts?

here's the modified checkpoint script

 RequireComponent(AudioSource);
 var audioSource : AudioSource;
 var announcer : AudioClip;
 var TimeExtensionText : GameObject;
 
 static var playerTransform : Transform; //Store the player transform
 
 function Start () {
 TimeExtensionText.gameObject.active = false;
     audioSource = GetComponent.<AudioSource>();
     playerTransform = gameObject.Find("player 1 car").transform; //Set the player transform
 }
 
 function OnTriggerEnter (other : Collider) {
     //Is it the Player who enters the collider?
 
     if (!other.CompareTag("Player 1")) 
         return; //If it's not the player dont continue
 
     //Is this transform equal to the transform of checkpointArrays[currentCheckpoint]?
     if (transform == playerTransform.GetComponent(TimerSystem).checkPointArray[TimerSystem.currentCheckpoint].transform) {
         //Check so we dont exceed our checkpoint quantity
 
         if (TimerSystem.currentCheckpoint + 1<playerTransform.GetComponent(TimerSystem).checkPointArray.length) {
             //Add to currentLap if currentCheckpoint is 0
         
             if(TimerSystem.currentCheckpoint == 0)
 
             TimerSystem.currentCheckpoint++;
 
         } else {
             //If we dont have any Checkpoints left, go back to 0
             TimerSystem.currentCheckpoint = 0;
                 
 
 
         }
         visualAid(); //Run a coroutine to update the visual aid of our Checkpoints
         //Update the 3dtext
     }
 }
 
 function visualAid () {
     //Set a simple visual aid for the Checkpoints
     for (objAlpha in playerTransform.GetComponent(TimerSystem).checkPointArray) {
         objAlpha.GetComponent.<Renderer>().material.color.a = 0.2;
     }
     playerTransform.GetComponent(TimerSystem).checkPointArray[TimerSystem.currentCheckpoint].GetComponent.<Renderer>().material.color.a = 0.8;
 }
 
 function AddTime(){
 TimeExtensionText.gameObject.active = true;
 
 TimerSystem.timeleft += 10;
 audioSource.PlayOneShot(announcer, 0.7F);
 DisableText();
 }
 
 function DisableText(){
   yield WaitForSeconds (2);
   TimeExtensionText.gameObject.active = false;
 
 }

and here's the original

 static var playerTransform : Transform; //Store the player transform
 
 function Start () {
     playerTransform = gameObject.Find("player 1 car").transform; //Set the player transform
 }
 
 function OnTriggerEnter (other : Collider) {
     //Is it the Player who enters the collider?
     if (!other.CompareTag("Player 1")) 
         return; //If it's not the player dont continue
         
     //Is this transform equal to the transform of checkpointArrays[currentCheckpoint]?
     if (transform == playerTransform.GetComponent(CarCheckpoint).checkPointArray[CarCheckpoint.currentCheckpoint].transform) {
         //Check so we dont exceed our checkpoint quantity
         if (CarCheckpoint.currentCheckpoint + 1<playerTransform.GetComponent(CarCheckpoint).checkPointArray.length) {
             //Add to currentLap if currentCheckpoint is 0
             if(CarCheckpoint.currentCheckpoint == 0)
                 CarCheckpoint.currentLap++;
             CarCheckpoint.currentCheckpoint++;
         } else {
             //If we dont have any Checkpoints left, go back to 0
             CarCheckpoint.currentCheckpoint = 0;
         }
         visualAid(); //Run a coroutine to update the visual aid of our Checkpoints
         //Update the 3dtext
     }
 }
 
 function visualAid () {
     //Set a simple visual aid for the Checkpoints
     for (objAlpha in playerTransform.GetComponent(CarCheckpoint).checkPointArray) {
         objAlpha.GetComponent.<Renderer>().material.color.a = 0.2;
     }
     playerTransform.GetComponent(CarCheckpoint).checkPointArray[CarCheckpoint.currentCheckpoint].GetComponent.<Renderer>().material.color.a = 0.8;
 }