Hi Maciej,
Thank you for your reply.
I think it is a multi-level issue and WPML is also playing a part here.
We made several tests, and the issue is only appearing when a custom Permastructure is set. When restoring all settings, everything is going normal.
Those duplicate posts are not visible in the WordPress back office, and we have to go in your URL Editor to find them and delete them.
I sent you the list of plugins used.
Kind regards,
Antoine
