Error updating sessions table

DEBUG MODE

SQL Error : 1062 Duplicate entry 'activity.php?game_name=boo&mode=highscore&page=high_scores' for key 'session_page'

UPDATE phpbb_sessions SET session_time = 1788986171, session_start = 1788986171, session_page = 'activity.php?game_name=boo&mode=highscore&page=high_scores' WHERE session_id = 'bee14f2ca7d02822b0451f25a936a304'

Line : 556
File : sessions.php