Error updating sessions table

DEBUG MODE

SQL Error : 1062 Duplicate entry 'viewtopic.php?download=-1&f=36&t=1323&_f_=36x&_t_=1323x' for key 'session_page'

UPDATE phpbb_sessions SET session_time = 1788990914, session_start = 1788990914, session_page = 'viewtopic.php?download=-1&f=36&t=1323&_f_=36x&_t_=1323x' WHERE session_id = 'bee14f2ca7d02822b0451f25a936a304'

Line : 556
File : sessions.php