Cannot redeclare class SuggarLogger

[TSA]

Hi,

I used previouly Sugar 4.5.0h.
I've first upgrade to 4.5.1l, seems that upgrade OK.

I've then upgrade from this fresh upgraded 4.5.1l to 5.1.0c.
At the end of the upgrade process, i had a error printed

Fatal error: Cannot redeclare class SugarLogger in /var/www/SugarOS-Full-4.5.0g/include/SugarLogger/SugarLogger.php on line 45

The line 45 is the main first line defining the class :

 class SugarLogger { 
  

Does somebody can explain me what's wrong ?
Thanks !

[TSA]

fIle include/SugarLogger/LoggerManager.php, line 88
replace :

 require('include/SugarLogger/'. $logger . '.php'); 
  

with

 require_once('include/SugarLogger/'. $logger . '.php'); 
  

Quite noob !