You could create the same problem with two clients and a script running on each.
But one is easier, and the question is why would you send coins to your own address?
It probably shouldnt be allowed.
your node splits up the 10coin-transaction into 2, 5coin-transaction to recipient + 5coin-transaction to yourself.
you not only can, the node has to send coins to yourself.
Thats something I didnt quite know, but the interface probably shouldnt allow it.
without leaving the node.
But using different addresses. You can send from address ABC to ABC right now which is what I did.