title: Problem attaching an entity in LINQ to SQL
body: <p>I'm trying to attach an entity in LINQ to SQL but it throws the following exceptionL: </p>
  
  <p><strong>An attempt has been made to Attach or Add an entity that is not new, perhaps having been loaded from another DataContext.  This is not supported.</strong></p>
  
  <pre><code>&lt;Table Name="dbo.Products" Member="Products"&gt;
      &lt;Type Name="Product"&gt;
        &lt;Column Name="Id" Type="System.Int64" DbType="BigInt NOT NULL IDENTITY" IsReadOnly="true" IsPrimaryKey="true" IsDbGenerated="true" CanBeNull="false" /&gt;
        &lt;Column Name="Name" Type="System.String" DbType="NVarChar(MAX) NOT NULL" CanBeNull="false" /&gt;    
        &lt;Column Name="IsDeleted" Type="System.Boolean" DbType="Bit NOT NULL" CanBeNull="false" /&gt;
        &lt;Column Name="Timestamp" Type="System.Data.Linq.Binary" DbType="timestamp NOT NULL" CanBeNull="false" IsVersion="true" /&gt;
        {...SOME ASSOCIATIONS....}
      &lt;/Type&gt;
  &lt;/Table&gt;
  </code></pre>
  
  <p>The code I use to attach the entity is: </p>
  
  <pre><code>var context = new MyDataContext();
  context.Products.Attach(entity, true);
  </code></pre>
  
  <p>Any idea, why I get this error?
  Thanks</p>