title: Find duplicate in List(Of T) using LINQ VB .NET not working
body: <p>I have a generic <code>List(Of T)</code> with a bunch of items that contain some duplicate values at <code>.ItemID</code>. I need the code to return only the duplicates, but my code below returns all of the items.</p>
  <pre><code>Dim items As List(Of ItemsClass.ItemCollection) = _
          New List(Of ItemsClass.ItemCollection)(oleObj.ListOfItemsToCopy(listViewItems)) 'Returns a list of items
  
  Dim duplicates = From c In items Where (c.ItemID.Count &gt; 1) Select c 'Needs to return duplicate items
  </code></pre>
  <hr />
  <p>An example of the <code>List(Of ItemCollection)</code> items are as follows</p>
  <pre><code>ItemID, Make,     Type     Year
  123456  Ford      Falcon   1999
  123457  Mazda     CX6      2001
  123456  Ford      Ranger   2002
  </code></pre>
  <p>I need to group the <code>ItemID</code> and return all of the duplicate results</p>