I'm using wp cli to import the same featured image for around 2,000 posts. I did a couple tests to see if the image would be duplicated or if WordPress would notice that the image already exists in the media library and use it. Sadly it just duplicates the image.
Command I'm using:
wp media import http://example.com/wp-content/uploads/sites/30/2016/04/picture_name.jpg --post_id=x --title="Pluto Mosaic" --featured_image --url=mysite.example.com
Is there another way to do this without having to import the same image 2,000 times?