Its those little tricks in terminology that get you. If the page had said charges up to two batteries then they would be independant, but when they say charges a pair of batteries then they are charging in series in parallel which not real good.
The other site where you see the AA battery holder with the little 9v snap on thing is probably doing the same and is probably a simple trickle charger with no charge termination.
Ever notice how when you buy a cordless phone for your home the battery pack dies in a year or two? They are typically series pair charging with a trickle charger. SO you must be careful if your going to rely on rechargeables in emergancy gear to charge them properly. You don't want to be using a trickle pair charger like those all the time then have an emergency and find out your batteries last 1/3 as long as they should. You want them to be working as their best at the start of the emergency so any damage/loss caused by those kind of chargers is minimized.
I switched to a digital camera over 10 years ago so I learned a lot about taking care of batteries along the way. I started out with not so great chargers and then after a while you find out the camera shuts off when you wanted to take a picture and you start to wonder why. Now my camera/GPS/radio/etc all run nice and long, usually my run time tests with rechargeables beat alkalines and are about even with lithium's.