Upgrade failure from 4.1.5 to 4.2.0, multilingual system

[Error: Upgrade DB to 4.2.alpha1: SQL]

DB Error: unknown error
#0 [internal function]: CRM_Core_Error::exceptionHandler(Object(DB_Error))
#1 /var/www/rie/administrator/components/com_civicrm/civicrm/packages/PEAR.php(931): call_user_func(Array, Object(DB_Error))
#2 /var/www/rie/administrator/components/com_civicrm/civicrm/packages/DB.php(968): PEAR_Error->PEAR_Error('DB Error: unkno...', -1, 16, Array, 'ALTER TABLE `ci...')
#3 /var/www/rie/administrator/components/com_civicrm/civicrm/packages/PEAR.php(564): DB_Error->DB_Error(-1, 16, Array, 'ALTER TABLE `ci...')
#4 /var/www/rie/administrator/components/com_civicrm/civicrm/packages/DB/common.php(1903): PEAR->raiseError(NULL, -1, NULL, NULL, 'ALTER TABLE `ci...', 'DB_Error', true)
#5 /var/www/rie/administrator/components/com_civicrm/civicrm/packages/DB/mysql.php(898): DB_common->raiseError(-1, NULL, NULL, NULL, '1060 ** Duplica...')
#6 /var/www/rie/administrator/components/com_civicrm/civicrm/packages/DB/mysql.php(327): DB_mysql->mysqlRaiseError()
#7 /var/www/rie/administrator/components/com_civicrm/civicrm/packages/DB/common.php(1216): DB_mysql->simpleQuery('ALTER TABLE `ci...')
#8 /var/www/rie/administrator/components/com_civicrm/civicrm/CRM/Utils/File.php(287): DB_common->query('ALTER TABLE `ci...')
#9 /var/www/rie/administrator/components/com_civicrm/civicrm/CRM/Upgrade/Form.php(152): CRM_Utils_File->sourceSQLFile('mysql://rie_joo...', '? ? SELECT @w...', NULL, true)
#10 /var/www/rie/administrator/components/com_civicrm/civicrm/CRM/Upgrade/Form.php(292): CRM_Upgrade_Form->source('? ? SELECT @w...', true)
#11 /var/www/rie/administrator/components/com_civicrm/civicrm/CRM/Upgrade/Form.php(316): CRM_Upgrade_Form->processLocales('/var/www/rie/ad...', '4.2.alpha1')
#12 /var/www/rie/administrator/components/com_civicrm/civicrm/CRM/Upgrade/Incremental/php/FourTwo.php(283): CRM_Upgrade_Form->processSQL('4.2.alpha1')
#13 [internal function]: CRM_Upgrade_Incremental_php_FourTwo::task_4_2_alpha1_runSql(Object(CRM_Queue_TaskContext), '4.2.alpha1')
#14 /var/www/rie/administrator/components/com_civicrm/civicrm/CRM/Queue/Task.php(79): call_user_func_array(Array, Array)
#15 /var/www/rie/administrator/components/com_civicrm/civicrm/CRM/Queue/Runner.php(173): CRM_Queue_Task->run(Object(CRM_Queue_TaskContext))
#16 /var/www/rie/administrator/components/com_civicrm/civicrm/CRM/Queue/Page/AJAX.php(44): CRM_Queue_Runner->runNext(true)
#17 /var/www/rie/administrator/components/com_civicrm/civicrm/CRM/Queue/ErrorPolicy.php(80):

{closure}

()
#18 /var/www/rie/administrator/components/com_civicrm/civicrm/CRM/Queue/Page/AJAX.php(51): CRM_Queue_ErrorPolicy->call(Object(Closure))
#19 [internal function]: CRM_Queue_Page_AJAX::runNext(Array)
#20 /var/www/rie/administrator/components/com_civicrm/civicrm/CRM/Core/Invoke.php(186): call_user_func(Array, Array)
#21 /var/www/rie/administrator/components/com_civicrm/admin.civicrm.php(87): CRM_Core_Invoke::invoke(Array)
#22 /var/www/rie/administrator/components/com_civicrm/admin.civicrm.php(40): civicrm_invoke()
#23 /var/www/rie/libraries/joomla/application/component/helper.php(383): require_once('/var/www/rie/ad...')
#24 /var/www/rie/libraries/joomla/application/component/helper.php(351): JComponentHelper::executeComponent('/var/www/rie/ad...')
#25 /var/www/rie/administrator/includes/application.php(153): JComponentHelper::renderComponent('com_civicrm')
#26 /var/www/rie/administrator/index.php(46): JAdministrator->dispatch()
#27

{main}

I have already tried CRM-10702 and it doesn't solve my issue.

Yves