I found a digg bugg today when I accidentally submitted an article twice via a dbl-click. It seems that the articles are given a unique key, however, the title doesn't seem to be checked for a duplicates when submitting. This allowed two articles with the exact same permalink.
The link given to the articles is here.
When following the link, one of the two seems to be randomly chosen for display (try F5 a few times). They have their own comments and own digg value. Without being able to delete something like this, it can cause confusion and server problems as the wrong one might be getting dugg, burried or commented on. I notified digg of the problem and hope it gets resolved.
In my submitted list, you can see the two diggs that i've marked dups.