That is because I have the featured image only set for the blog intros (home page showing all posts) but not on the full post view (single post view). I’m about to make some adjustments to the Celestial Reloaded theme to use the excerpt method but discovered I have to change a couple other files too.
When done, you can use the Featured Image, then if you insert the image (even if it’s a different size or orientation) into your post, this won’t show as a double image on your blog home page as it does now. Likewise, the Featured image will only show on the blog part but not the full post.
Basically the featured image will show on the blog posts view, and your own inserted image won’t, but it will for the full post view.