You have found, as others have, that with some printer drivers the settings changes you make (e.g., number of prints) seem to be staged in some intermediate place, so what happens is that the number of copies you wanted for this print will end up happening for the next print. This happens with other settings as well.
There's a workaround being reported that causes the settings values to be transmitted to the printer without actually going through the print process... This works for some folks:
- File - Print in Photoshop.
- In the Photoshop Print dialog, set the number of Copies.
- Click the [Print Settings...] button.
- [OK] out of the printer settings dialog.
- Now click [ Print ].
See also this thread: http://forums.adobe.com/thread/835654