title: DataTable.AsEnumerable().Distinct() doesn't work because of primary key column
body: <p>I want to remove duplicates from my <code>DataTable</code> so I'm using <code>DataTable.AsEnumerable().Distinct(DataRowComparer.Default)</code> but it doesn't do what I need. I think because each duplicate row has it's unique primary key column.</p>
  
  <p>How can I do what I need? Write my own <code>DataRowComparer</code>? I don't want - because the default must works.</p>