(It's 2d6 plus modifiers vs. some difficulty number, by the way)
But the GM never rolls dice. And in contests between players, only one of them rolls dice. Now this might leave some players thinking that they aren't involved in a contest, and to a small degree that's true. However, the flipside is that if a player wants to have that kind of involvement in a scene, they need to drive it themselves. This is an emergent phenomenon of the resolution system. Players are driving the details of the story, whereas the GM is operating at a macro level, driving the plot and giving plenty of opportunity for tension and trouble.