Browser Refresh Adds To Cart

Hi – I’m using my own add-to-cart button on my Download pages, but on the press of that button I would like the user to stay on the Download page. My current button code:

<a href="?edd_action=add_to_cart&download_id=<?php echo get_the_ID();>

The above code achieves this, but then each refresh of the browser causes another download to be added to the cart. Is there an alternative way to stay on the page without this side effect?

(Ajax is not disabled if that has any relevance).

Any suggestions much appreciated.

http://wordpress.org/plugins/easy-digital-downloads/