@contactwis We’re sorry to hear you are experiencing this issue on your site.
We checked on the URL of the example page you provided and reviewed the source code and only see a single meta description being output, which is the following:
<meta name="description" content="En entreprise, la communication et les échanges avec les partenaires et les clients représentent un besoin fondamental. C’est pourquoi des moyens de plus Cloud Eco est une structure qui aide les entreprises à mettre en place une méthode de communication performante : la téléphonie sur IP." />
If you clear your cache (server, plugin/theme, browser, or CDN such as Cloudflare) does this resolve the issue with seeing a second meta description output? If you are not sure how to clear your server cache you should speak with your host provider. We have information on how to clear your browser cache at the following link: https://yoast.com/help/how-to-clear-my-browsers-cache/.