How to show registration page in another language, maintaining its natural behaviour? I need to show my registration page in another language, keeping this separate from his natural behaviour. In particular this page must be showed in English on the page of the site it owns to, but i need to show it in Italian on another site into an iframe. Now, common sense tells me i need a page

 www.example.com/user


and a

 www.example.com/it/user


and i tried to achieve this by "admin/config/regional/language/configure" and the option "Determine the language from the URL (Path prefix or domain)." and all works fine, but, for some reason, as i activate this option, ALL my site pages get a "/en/" in their url, breaking a lot of things into the site (that is extremely complex). There's a way to achieve this behaviour for the registration page only? (be able to call a page www.example.com/it/user to show registration in italian and having www.example.com/user and all other pages in the site work without any changes?)
Navigate to /admin/config/regional/language within your site, and verify these things (and correct where appropriate):


Use "English" as your default language
use the "Edit" link for "English" on that page, which will bring you to "/admin/config/regional/language/edit/en". On that page, make sure the value for "Path prefix language code" is "blank".