Upgrade 6.3.7=> 6.4.4

Hi the community,
I write a message here because I have no solutions to my issue.
I want to upgrade Projeqtor.
I follow the indications when I see the login screen I just put my admin account.
And Projeqtor say that my upgrade had two ERRORS and I Have to go to log file.
Here I see :
VERSION V6.4.3
2017-11-17 14:27:44.791 ===== TRACE =====
2017-11-17 14:27:44.792 ***** ERROR ***** [V6.3.7] Exception-[23000] SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '50' for key 'PRIMARY'
2017-11-17 14:27:44.792 ***** ERROR ***** [V6.3.7] For query : INSERT INTO `importable` (`id`,`name`,`idle`) VALUES
(50,'Tender',0),
(51,'CallForTender',0);
2017-11-17 14:27:44.792 ***** ERROR ***** [V6.3.7] Strack trace :
2017-11-17 14:27:44.792 ***** ERROR ***** [V6.3.7] #0 Sql->query called at [/var/www/projeqtor/db/maintenanceFunctions.php:71]
2017-11-17 14:27:44.792 ***** ERROR ***** [V6.3.7] #1 runScript called at [/var/www/projeqtor/db/maintenance.php:101]
2017-11-17 14:27:44.792 ***** ERROR ***** [V6.3.7] #2 include called at [/var/www/projeqtor/tool/loginCheck.php:135]
2017-11-17 14:27:44.792 ===== TRACE =====
2017-11-17 14:27:44.792 ===== TRACE ===== Error # 1 => SQL error while executing maintenance query for version V6.4.3 (see above message)
2017-11-17 14:27:44.792 ===== TRACE =====
2017-11-17 14:27:44.792 ===== TRACE ===== *************************************************
2017-11-17 14:27:44.792 ===== TRACE =====
2017-11-17 14:27:44.792 ===== TRACE =====
2017-11-17 14:27:44.792 ===== TRACE ===== DATABASE UPDATED
2017-11-17 14:27:44.792 ===== TRACE ===== WITH 1 ERROR

By the way I am on a virtual Machine so I made snapshots it is the fourth time I try upgrade my Projeqtor...

Yes, I still forget : I can enter in projeqtor but there are some display problems there were not before the upgrade