Duplicate Meta Description Problem

If you have two urls leading to the same content, you could use your Yoast SEO plugin to specify a canonical url. This is the url by which you would like the content to be indexed. If both urls lead eventually to the same canonical url, that should fix the issue. I think the default is that the canonical url field is blank and in the page markup it defaults to the actual url, which in this case you don’t want. Anyway, that’s my understanding but too big a job for me to test if this is correct.