title: linq query displaying result twice
body: <p>pd is my page ;</p>
  
  <pre><code>ProductDetail pd = new ProductDetail();
  </code></pre>
  
  <p>fetching data and strong it in data</p>
  
  <pre><code>var data = 
      from product in db.Products
      from orders in db.Orders
      from od in db.OrderDetails
      from dpt in db.Dpts
      where orders.CId.Equals(
          (from name in db.Companies
          where name.Cname.Equals(selectedcomp)
          select name.CId).FirstOrDefault())
      &amp;&amp; od.OrdId.Equals(orders.OrdId) 
      &amp;&amp; product.PId.Equals(od.PId)
      select new 
      { 
          orders.Billno , 
          orders.Date, 
          orders.pharm ,
          product.Pname,
          product.Purchasedate,
          product.Purchaserate,
          product.Salesrate,
          product.Supplier,
          od.Quantity,
          od.Amount
      };
  </code></pre>
  
  <p>it displays the value of data twice in listbox. </p>
  
  <pre><code>pd.ProductDescription.ItemsSource = 
      (from dat in data
       select dat).ToList();                                    
  </code></pre>