Nutrition Facts Question

Okay, I'm not sure if this was a mistake on the box or if I am missing something.

I ate the weight watchers dark chocolate raspberry ice cream bars and on the box it says :

2 bars equals one serving

one bar is 80 calories
two bars equals 170 calories.


Last time I checked, 80 * 2 = 160..... NOT 170

am I missing something here?