Ya know, I was checking the air pressure in one of our duallies Monday...
Both outer rear rims had 2 valve stems each. I didn't pay attention to the fronts... only noticed it on the rear since I had to reach in there for the inner rim.
And I just thought of something my Voc Auto instructor in HS told us. He said when he was a teen and working at the service station, he would ask the hot women if they changed the winter/summer air in their tires. Most didn't know anything about cars, so he told them he'd do it for free! All just so he could check them out longer...