Menu links duplicated on node/%node/edit pages
I'm not sure i fully understand the question, but please take a look to this post:

https://drupal.stackexchange.com/a/96963/30465

It seems related to your question.

I this it will be related to the language configuration fallback (since there is no language suffix inlcuded)

You could for example try

http://www.example.com/en/node/%nid/edit

if that works correctly (and only shows the engish menu links), you know that it will be a problem with language fallback.

Hope this helps, feel free to let me now if you need more!! :)