Attached is a link to a test file.
Create a new game in build 798 and load this custom quest. Grab the sword on the first screen and use it to open the chest on the second screen. Get the item. Move off the screen and return. The item does not reappear, which is expected.
Now, try the same thing in build 809 or 813. Instead of the item only appearing once, it appears every single time.
I have also repeated this problem in the Hidden Duality: Director's Cut quest:
Enter level 1, then go right one screen and up two screens to get to the room with the compass.
Test file:
http://rapidshare.com/files/121082469/bugtest809.qst.html