Such cunning dice…

I was at Toys”R”Us today and i saw these two dice. Says it’ll always show 7 and 11. So i shook the box and what do you know, a 7. I shook it again, 11. And again, 11. Hmm… amazing. I thought the die was most likely biased and it tends to fall on 5, 2 and 6. Then my friend said, ‘Aiya, like that of course always 7 and 11’. O.O Could there be a more simpler explanation for it?? I examined the dice this time and i was like –> …… –.-‘ What the heeeck! One die is all 5’s and the other is either 2’s or 6’s. –.-‘’ Sweat~