@royeti
As I said, this is not a theme issue.
1. You mentioned:
Why? With other themes it works ok.
But as I tested sharing a single post using Twentyfourteen theme the title and date is also included on the sharing description.
2. It seems AddThis, or more specifically Facebook gets the description by searching the page for a meta description. This is plugin territory and can not be controlled by a theme since themes must conform with the WordPress theme guidelines. https://make.www.ads-software.com/themes/guidelines/guidelines-plugin-territory/
on your site ronangelo[dot]com is the same problem when sharing on facebook: title(bold) then again title,date,contant, next / prev links
Could you check again? I have meta descriptions through a plugin and as I test sharing a page there are no title duplication or date on the description.
Also, I’m using Frontier theme on my own blog, not Asteroid. I was originally referring to another site using Asteroid theme the same as you. You could test sharing a post https://dyi.li/4Um