colliding with 2 objects at a time

i have a moving cube and when it collides with 2 cubes at once I would like to destroy the one that I collided first and not both of them

I am using this script for destroying

     function OnCollisionEnter(col : Collision)
         {
              if(col.gameObject.name == "block(Clone)") 
             {   
                    if(col.gameObject.GetComponent(materials).curTxt == 1){
                            ActiveDig = true;
                         score += 100;
                         yield WaitForSeconds (2  / drillSpeed);
                                            Destroy(col.gameObject);
                    }