'multiple' option not working correctly, e.g. og:see_also

This new release allows to use Open Graph's see_also tag: under the Open Graph tab, there is now a "See also" field.

Adding a single URL in this field provides a new meta tag, for instance:
<meta property="og:see_also" content="https://twitter.com/drupal" />

But adding multiple URLs in this field does not provide multiple lines of meta tags: all meta tags are listed in the same line of code.

I tried to separate each URL with:

• a comma
• a comma + a blank space
• a semicolon
• a blank space

In D7's metatag module, you just have to separate each URL with a comma + a blank space to generate multiple lines of meta tags.