Twenty Twelve Featured Image Showing up twice

I added the following to my default child theme content.php

<?php the_post_thumbnail(‘thumbnail’, array(‘class’ => ‘alignleft’)); ?>

Once I did it moved my thumbnail to the left which is what I want and it moved my test to the right of my thumbnail.

My issue is that I now have two thumbnails on my index.php page and the thumbnail also shows up on my post page. I need to remove the additional thumbnail from the index.php page and remove the thumbnail from my post page.