The reason why it shows a double post image on the blog listing page is that:

1. You have added the read more tag in the blog content to show the intro text + image on the blog listing page.

2. At the same time, you have enabled this "First Image as post cover" setting (screenshot: https://monosnap.com/file/NR6r83r02AVdiSDLVNmLunYamytf0o ) so the system will pick the first image as post cover and show on the blog listing page as well.

To prevent this, I will suggest you turn off this "First Image as Post Cover" setting from the backend > Easyblog > setting > layout > post covers.