Random Obstacle Placement

Hi, i'm working on a script for a endless runner game in which you have to jump over some obstacles. Now I've made a script which randomly places obstacles, however sometimes it places obstacles on the same place. I also use object pooling. Could someone please help me?

 public class GroundGenerator : MonoBehaviour {
 
     public GameObject theGround;
     public Transform generationPoint;
     public float distanceBetween;
 
     private float groundWidth;
 
     public ObjectPooler theObjectPools;
 
     public float randomSpikeThreshold;
     public ObjectPooler spikePool;
 
 
     // Use this for initialization
     void Start () {
         groundWidth = theGround.GetComponent<BoxCollider2D>().size.x;
 
     }
     
     // Update is called once per frame
     void Update () {
 
         if (transform.position.x < generationPoint.position.x) 
         {
             transform.position = new Vector3 (transform.position.x + groundWidth + distanceBetween, transform.position.y, transform.position.z);
 
             //Instantiate (theGround, transform.position, transform.rotation);
             GameObject newGround = theObjectPools.GetPooledObject();
 
             newGround.transform.position = transform.position;
             newGround.transform.rotation = transform.rotation;
             newGround.SetActive (true);
         }
 
         if (Random.Range (0f, 100f) < randomSpikeThreshold) 
         {
             GameObject newSpike = spikePool.GetPooledObject ();
 
             float spikeRandomiser = Random.Range (-14f, 14f);
 
             Vector3 spikeSposition = new Vector3 (0f + spikeRandomiser, 2f, 0f);
 
             newSpike.transform.position = transform.position + spikeSposition;
             newSpike.transform.rotation = transform.rotation;
             newSpike.SetActive (true);
         }
     }
         
 }

,