I see duplicated submissions in the Director's role at .../director/submissions/submissionsUnassigned, with almost the same behavior that Renato's case:
viewing in the default language (es_ES) you see some duplicated submissions, but viewing in other languages (en_US, pt_BR) you see just one line for each submission .
When any user want to upload a submission in a different language than spanish (default),
after clicking "Save and continue", in the 2nd step, a validation message appears:
Errors occurred processing this form:
* Please enter the title of your paper. (Español)
* Please enter an abstract for your submission. (Español)
filling both fields and clicking again "Save and continue", the submission process finishes normally.
That results in two registers in paper_settings table: one with the formers language and another in spanish (locale = es_ES).
I dont know if this could be the reason but it's the only clue I have found...