eliminar repeticion

app/models/Activity.php

     $activity_criterion = DB::table('activity_criterion')
       ->join('criteria', 'criteria.id', '=', 'activity_criterion.criterion_id')
       ->where('activity_id', $this->id)
+      ->select('activity_criterion.activity_id', 'activity_criterion.criterion_id', 'criteria.*')
+      ->distinct()
       ->get();
 
 
     //return json_decode($this->outcomes_attempted, true);
     return $outcomes_attempted;
   }
-}
+}