But this document wasn't visible in the Webinterface. Even for me as admin. If i Uploaded the Document through the webinterface, the filename change to "filexy-1.pdf"
Is it viewable on the CIFS ? chances are there that prior to completion of the upload event on CIFS, an attempt has been made to view it on the web and did a upload, so it recreated filexy-1.pdf in share. But if you are sure and could replicate the issue, then it seems to be an issue.