Comment 6 for bug 971147

I have just tried to reproduce this on Ubuntu 13.10, but could not do so.
I noticed however, that the window gets moved sometimes from the right to the left screen, but sometimes only to the upper left of the right screen.

Besides, for moving a window to the next/previous output, you can use Unity's "Put" plugin. I have mapped Ctrl-Alt-n to move a window from one output to the next.