SQL-DATABASE ERROR

Database error in WoltLab Burning Board (2.3.6 pl2): Invalid SQL: INSERT INTO bb1_sessions (sessionhash,userid,ipaddress,useragent,lastactivity,request_uri,styleid,langid,authentificationcode) VALUES ('9e83d18df9a7328d798b819a0dc2718a','0','38.107.179.219','CCBot/1.0 (+http://www.commoncrawl.org/bot.html)','1328478267','thema18156.htm','0','0','')
mysql error: Duplicate entry '9e83d18df9a7328d798b819a0dc2718a' for key 1
mysql error number: 1062
mysql version: 5.0.67
php version: 4.4.8
Date: 05.02.2012 @ 22:44
Script: /thema18156.htm
Referer: