Browser: Google Chrome
Operating System: Windows Vista
I added some manga books (#34 to #39) to this page: http://www.animevice.com/historys-strongest-disciple-kenichi/15-263/
But after some time, I received 30 points from a duplicated manga book (the #36) that I didn't add. You can see the duplicated manga books in the list of books of the link above.
As an extra information, I had problems when I tried to add the book #36, so I had to refresh the page (2-3 times) to add the book, and when it was added to the list it wasn't duplicated (at that moment).
Regards! and thanks...