Few months ago I was flying with LH on route IAD-MUC and carried 18 laptops with my colleague (so each had 9) in carry-on luggage and there was no problem at all. The TSA guys were only joking with us and normally screening each laptop separately. I don't think that they care too much if you carry one or ten laptops as far as they aren't a security concern. You bigger concern is the customs, but I don't think that they will make you a problem if you convince them if one is private and the second laptop from your company.
If you are wondering why we had so many laptops - we got them as a donation from an US company to an organisation in which we are involved. Hopefully we passed the customs without problems, otherwise it would be hard to explain the term "donation" to them...