[ic] Reloading page causes new item to be added

[interchange-users@icdevgroup.org (Interchange User)]

Hi, I wonder if anyone noticed from the live demo store, that if you 
do the following:

1) click on "More Info" for an item (to go into the flypage), 
2) click "Buy Now"
3) at the "basket" page, press ctrl-r (or click the "reload" button 
on the browser) to reload the page

...a new item (same as the previous) will be added into the cart?

That's bad...
How can we overcome this problem?