whats your situation? traveling alone or with others(family).
i would say spread the MBAs around to other passengers in your party if you can. carrying 2 sealed boxes on one persion will be suspicious. not just to TSA on our shores, but to customs on the other side. unless you are planning to pay them off to look the other way, they may want to know why you are bringing them. if you say they are for friends, either as gifts for for sale, they will want taxes/tariffs/duties. professional samples require further business related explanations etc.
easiest thing to do is open the boxes, keep the MBAs in laptop bags in your carryon, and put the boxes and other crap in your checkin. let your brother carry one and you the other and declare them as personal items, nothing suspicious about that.
then when you get to your place, rebox them to give to your friends and be done with it. they should understand that you had to open them and you are doing them a favor. luggage allowances are slim and every ounce is valuable.
also opening them gives you the opportunity to inspect them and get any problems fixed here. Apple in the US is probably going to be more generous with swapping defects than overseas (as evidenced in these forums by someone going back 6 times).
if they are for other purposes and really need to be sealed, there is nothing special about the shrink wrap apple uses, so you can easily repackage them and reseal them if you needed to.