PROBLEM: Chapter 14, ManagePhotoAlbum.aspx. On this page, insert a picture, this works fine. Then click the browser refresh and the same picture is inserted again. Repeat and it happens again.
CONTEXT: I wasn't entirely sure if it was something in my project. So I went to your site: http://aspnet4.planetwrox.com/
and I reproduced the error. If you look at album "testt", the duplicate images were produced by me clicking the browser refresh. To reproduce error, just insert an image and then click the browser refresh.
QUESTIONS: 1) Why does it happen? I looked at the code, life cycle, etc. and conceptually, I don't understand why it happens. 2) Can you provide a fix?