Hello. I understand that double-sided printouts will smudge, if printing on draft mode. Personally, I would suggest printing using the "best quality" setting. This usually eliminates any smudging that can occur, in situations similar to this.
Additionally, I would utilize ColorLok paper when printing, in this situation. For more information on this paper, please reference this HP website: http://www.hp.com/sbso/product/supplies/paper_colorlok.html
Please respond if you have any other questions or concerns. I'm only here to help!
Mario