WordPress: 2 meta description tag and Yoast

Question

I am currently learning about SEO in general. I am studying a website that uses WordPress CMS.

First question. When viewing the page source, I notice there are two meta tag for description in the page?

The one below is the first appreance for <meta name="description"> it is located at the first few lines of the page source.

I am not sure if it is because the website is using Yoast, thre is another occurrence of <meta name="description">, picture below:

I realized that when using the snippet editor of Yoast, the value for <meta name="description"> that occurs later in the page and the value for <meta property="og:description"> will be updated. The <meta> tag that occurs first at the top of the page source will remain blank.

EDIT: I understood why the 2nd <meta name="description"> tag will be generated. It is generated because under 'Search appearance' settings in Yoast SEO. There is a meta description template which will apply for all elements of a content type. (e.g. pages/posts/)

The first meta description tag is placed inside header.php inside the theme folder of the theme the CMS is using. The second meta description tag is generated by Yoast SEO.

Answer 1

Both do actually very marginally (if at all) affect SEO. They are mainly used for showing short descriptions of your page, if your site is linked on other sites.

<meta name="description"> may (you have no certainty) be (partially) used by search-engines (see Google's support page on meta tags the Googlebot understands)

<meta property="og:description"> (Open Graph description) may be used by social media networks like Facebook. For instance, the Open Graph protocol is used on Facebook to allow any web page to have the same functionality as any other object on Facebook.

Using both (with useful content) won't hurt.

To combine them (Schema and Open Graph) see combining the meta description and open graph protocol description into one tag and is it possible to use the same meta tag for opengraph and schema.org (both on StackOverflow).