No.
-Char A is in the lagged game (Bnet doesn't think its there, but you will still save when leaving)
-Char B (actually just another char A), makes a new game (which is possible b/c bnet thinks char A's game doesn't exist)
-Char C (A new character) joins char B's game. Char B xfers the items to be duped to char C. They leave.
-Char A leaves its game.
Now, you will have transferred Char A's items to a new char, but then restored the items. Hence, duped items.
But, as said, you need to actually have sufficient SERVER-side lag in char A's game before Char B can make a new game wth the same character. Considering that we don't have direct control over this aspect of the server, it becomes quite difficult to purposefully create enough lag...hence the difficult part. Then again, it actually says nothing about creating lag, more of a just wait for a lucky opportunity, and when it comes, quick call a friend.
But, people are impatient...