I'm for allowing to edit your own root nodes, however, your justification isn't the best of reason.

The main reason why there are so many duplicates is because it is so damn easy to submit the same preview twice, and have it appear as a new node, twice. It happened to me, once, and I swear, it was by accident.

We've been over this a few times in the Chatterbox, and having a unique preview ID, and only accept final submission for it once, sounded like the most sensible option. I recall you agreed to that. Only, someone still has to do the job, and implement it. :)