Hi ludo974
Basically in Joomla article, it has intro text and full text and the 'readmore' button will divide these 2 parts of an article.
I checked the 'Villa dans l'Ouest' article on your site and there is no readmore there so it will consider all text as full and show in both intro text + full text on frontend.
I just added for you and it shows correctly now.
Regards