Not really related to plugin.
Your site should serve "one" version of your pages ideally, meaning either
http://yoursite...
or
http://www.yoursite....
this should match in your hosting setup, sitelinks, and sitemap.
You can try setting the explicit domain in your wp-config.php file -- see the WordPress.org codex on how to do that (how to edit wp-config file).
You can also, I think, tell Google in your search console which version of pages is correct (either www or non www).
But WordPress should only be serving up one or the other, and auto redirecting the other format.
If you changed the format moving from static page to wordpress (which defaults to *no* www) you can try doing global 301 redirect for any queries for www to non www version.
But, again -- links on your site, site setup, default hosting setting, should be set to *one* version explicitly; typically this is the non www version since www is redundant (www = world wide web which it is obviously).
