Changing meta tags

Hi.
I have developed a single page / one page website. By scrolling down at this website the URL in the address bar will automatically changed via HTML5 History API. I’m not sure how I should handle with the search machines. I have in the Yoast SEO Plugin for every view (page) on my single page set a meta description. But the meta is not replaced (because => single page). My question are: When the url will changed, should then I also change the meta? Will the search machines notice that?
My other question is: Is for search engines the request of all this URLs to the single page, duplicate content?

Thanks for answering.