Hi Brent,
Yes, you’re correct, displaying a Content Template on a single post should replace the Content of the Post, and you shouldn’t have to exclude something that isn’t included in the display rules location. However, as is, it seems that there are 2 Content Templates displayed in both posts.
While viewing the post, can you hover on Elements in the admin bar, and check which Content Templates are displayed?: https://share.getcloudapp.com/BluGdlJD
Check if their display rules location are set properly.
Kindly let us know how it goes.