Distributor
Content creators using WordPress will love the Distributor plugin as it allows you to share, publish, and auto update content between various WordPress websites.
Takes care of SEO issue for duplicate content
You can pull and push content among different websites with the back-end power of REST API. It also takes care of any SEO issue that might result from the same (duplicate) content on multiple websites with the option of canonical meta tags.
Requires free registration for updates
Also, you can automatically push future updates from the original to other copies as long as they are connected. While this plugin is free, you need to register for free to receive updates.