Could not insert search results

DEBUG MODE

SQL Error : 1062 Duplicate entry '728692775' for key 'PRIMARY'

INSERT INTO phpbb_search_results (search_id, session_id, search_time, search_array) VALUES(728692775, 'b4e2fb7b99711f6a448c6e59859579d4', 1766326149, 'a:7:{s:14:"search_results";s:46:"167269, 167432, 167534, 167551, 167552, 167567";s:17:"total_match_count";i:6;s:12:"split_search";N;s:7:"sort_by";i:0;s:8:"sort_dir";s:4:"DESC";s:12:"show_results";s:5:"posts";s:12:"return_chars";i:200;}')

Line : 706
File : search.php