Remove Featured Image in Full Post, on home page.

Hi all,

I’ve followed these instruction in order to get full posts on the homepage. It worked very well. http://www.onedesigns.com/support/topic/full-posts

On problem I’m getting now is a duplicate of the same image. You can take a look at it : http://mtlinstantane.com/ (french)

I’m getting that because the first image of the post is always the featured image (that’s part of our concept…).

How can I disable the featured image on full post, i.e. the one called the_content ?
Thanks !