I've often travelled with two or more notebooks and not experienced any problems other than the predictable slow down at security to get everything out and on to its own pallet to be x-ray'd. As others have suggested, make sure you can 'log on', get rid of receipts, know your way around them, and a good explination at hand. In my case, it's normally a standard work machine and a demo machine (both IBM Thinkpads), and a personal machine (Apple TiBook), all easily demonstrable if the security people are interested.
I also try to leave everything in standby mode to simplify the impromptu sales pitch.
[This message has been edited by michswiss (edited 08-25-2003).]