YES! And I've seen it happen more than once, usually after another (successful) move, with SM v11.x. The messages are sometimes copied rather than moved.
I have learned to check the source folder to make sure those messages are not still there after the "move", deleting them if they are.
I have not, however, seen the duplication that you mention. Sounds like, in both cases (messages copied and not moved, and the duplication issue), something in the "move" process is timing out, and SM may be re-trying the operation. But I'm really not sure exactly why this occurs.