Hello,
When creating SEF URLs, parameters 'itemid' and 'Itemid' considered as different, and create a duplicate URL. For example,
Correct:
en/downloads/databases
index.php?option=com_content&catid=13&id=367&lang=en&view=article&Itemid=159
Wrong (duplicate):
en/downloads/databases
index.php?option=com_content&catid=13&id=367&itemid=159&lang=en&view=article&Itemid=159
Thanks.