Featured Image dupication in posts

I’ve just recently moved my posts over from a wordpress.com site – I’ve managed to figure out lots of the differences in this theme on .org but my features images are appearing twice in each post – once at the top of the post (above the title, in a cropped format) and then again in the position I’ve placed them.

Does anyone know how I can fix this? (baring in mind that I’m pretty new at this!)

Thanks in advance for any help.
(the site is http://www.postcardtohome.com)