Error: mdb->get_record() found more than one record!

• line 1636 of /lib/dml/moodle_database.php: call to debugging()
• line 1697 of /lib/dml/moodle_database.php: call to moodle_database->get_record_sql()
• line 4839 of /backup/moodle2/restore_stepslib.php: call to moodle_database->get_field_sql()
• line 137 of /backup/util/plan/restore_structure_step.class.php: call to restore_create_categories_and_questions->process_question_hint()
• line 121 of /backup/util/helper/restore_structure_parser_processor.class.php: call to restore_structure_step->process()
• line 178 of /backup/util/xml/parser/processors/grouped_parser_processor.class.php: call to restore_structure_parser_processor->dispatch_chunk()
• line 109 of /backup/util/helper/restore_structure_parser_processor.class.php: call to grouped_parser_processor->postprocess_chunk()
• line 148 of /backup/util/xml/parser/processors/simplified_parser_processor.class.php: call to restore_structure_parser_processor->postprocess_chunk()
• line 92 of /backup/util/xml/parser/processors/progressive_parser_processor.class.php: call to simplified_parser_processor->process_chunk()
• line 190 of /backup/util/xml/parser/progressive_parser.class.php: call to progressive_parser_processor->receive_chunk()
• line 278 of /backup/util/xml/parser/progressive_parser.class.php: call to progressive_parser->publish()
• line ? of unknownfile: call to progressive_parser->end_tag()
• line 179 of /backup/util/xml/parser/progressive_parser.class.php: call to xml_parse()
• line 158 of /backup/util/xml/parser/progressive_parser.class.php: call to progressive_parser->parse()
• line 110 of /backup/util/plan/restore_structure_step.class.php: call to progressive_parser->process()
• line 181 of /backup/util/plan/base_task.class.php: call to restore_structure_step->execute()
• line 178 of /backup/util/plan/base_plan.class.php: call to base_task->execute()
• line 168 of /backup/util/plan/restore_plan.class.php: call to base_plan->execute()
• line 385 of /backup/controller/restore_controller.class.php: call to restore_plan->execute()
• line 3504 of /course/lib.php: call to restore_controller->execute_plan()
• line 2594 of /course/format/smartopal/lib.php: call to duplicate_module()
• line 1894 of /course/format/smartopal/lib.php: call to format_smartopal->duplicate_section()
• line 1033 of /lib/pagelib.php: call to format_smartopal->page_set_course()
• line 2822 of /lib/moodlelib.php: call to moodle_page->set_course()

i pay attention that have a problem in the type drag and drop into text 

process_question_hint call to get_field_sql and then get_record_sql and there we have a function that check if there are more then one record in the table and of course we don't have because we have two hints(look explain in the image documentation  ).

how i solve that problem?
this happen when i try duplicate a section with that type question inside section.