Error updating sessions table

DEBUG MODE

SQL Error : 1062 Duplicate entry 'viewtopic.php?download=41573&f=80&t=3503&_f_=80x&_t_=3503x' for key 'session_page'

UPDATE phpbb_sessions SET session_time = 1777879880, session_start = 1777879880, session_page = 'viewtopic.php?download=41573&f=80&t=3503&_f_=80x&_t_=3503x' WHERE session_id = 'fa9d61cf3adef7fae90916a11d43946a'

Line : 556
File : sessions.php