I have done exchanges through Amazon a lot,they are very very good to work with,so if it bothers you(which it surely would me)I would email them,or better yet call them,and get it swapped out,usually they rush you a new copy overnight and then you send the other one back to them,if I remember right I think they give you a return label as well,but if not 1 DVD does not cost much to send anyways.
let me know if you got the file in your email.