Fixed issue Item with the same ID X already exists

Author: ihorvansach

Model/ResourceModel/Category/Collection.php

@@ -196,6 +196,8 @@ protected function _renderFiltersBefore()
                 ['store_table' => $this->getTable('magefan_blog_category_store')],
                 'main_table.category_id = store_table.category_id',
                 []
+            )->group(
+                'main_table.category_id'
             );
         }
         parent::_renderFiltersBefore();

Model/ResourceModel/Post/Collection.php

@@ -400,6 +400,8 @@ protected function _renderFiltersBefore()
                     [$key.'_table' => $this->getTable('magefan_blog_post_'.$key)],
                     'main_table.post_id = '.$key.'_table.post_id',
                     []
+                )->group(
+                    'main_table.post_id'
                 );
             }
         }