title: While Batch Inserting to Mongodb WriteConcern detected an error 'E11000 duplicate key error index
body: <p>I am creating a <code>List&lt;MyCollectionItem&gt;</code> 
  and use insertbatch method to insert the list. (<code>_collection.InsertBatch(entities)</code>)</p>
  
  <p>I do not set an id to MyCollectionItem object.
  And I expect mongo to set the id.</p>
  
  <p>It throws the exception 
  <strong>Unable to write data to the transport connection: An existing connection was forcibly closed by the remote host.</strong>
  and when I look at the write concern I see this error <strong>WriteConcern detected an error 'E11000 duplicate key error index:</strong> </p>
  
  <p>but the items count that i send to method and the inserted items in db are same...
  seems it successfully inserted all the data...</p>
  
  <p>How can i fix this? Where should I check?</p>
  
  <p>the index info is here...</p>
  
  <pre><code>{MongoDB.Driver.IndexInfo}
  DroppedDups: false
  IsBackground: false
  IsSparse: false
  IsUnique: false
  Key: { "_id" : 1 }
  Name: "_id_"
  Namespace: "MyDB.MyCollection"
  RawDocument: { "v" : 1, "key" : { "_id" : 1 }, "ns" : "MyDB.MyCollection", "name" : "_id_" }
  TimeToLive: {10675199.02:48:05.4775807}
  Version: 1
  </code></pre>