Hmm, I tried myself.
If I am pressing "Get It!" on page
http://www.abandonia.com/en/downloadgame/44, I am receiving page about donations AND my download.
But if I am trying to access directly
http://www.abandonia.com/donation/44 , it will be only donations.
So suggestion: as it seems relate on
previous page, it must be referrer. Could you disable it somewhere?
I think, most browsers have such ability.