I've got the following left join in my `_prepareCollection();` method: $collection->getSelect()->joinLeft( array('views_index' => "my_views_table"), 'views_index.entity_id = main_table.entity_id', array('views'=>'count') ); And then in my `_prepareColumns()` method I have: $this->addColumn('views', array( 'header'=> $this->__('Views'), 'index' => 'views', 'width' => '5%', 'filter_index' => 'views_index.count' ) ); When I load this page though, I get an error: > Item (Namespace_Module_Model_Mymodel) with the same > id "{ID}" already exist How is this conflict occurring? Some background: [Magento Custom Grid Redirect Error (On Join Attributes ONLY)][1] Would appreciate any help [1]: http://magento.stackexchange.com/questions/33943/magento-custom-grid-redirect-error-on-join-attributes-only