How to counter this Sheriff of Nottingham strategy?

Two of my game night group members developed a strategy for Sheriff of Nottingham which I’m not sure how to counter. They basically make a deal at the start to let each other smuggle as much contraband as they want when they are sheriff. Then, the two of them collect an absurd amount of contraband and pretty much guarantee that one of the two of them will win. I could maybe pair up with someone like that myself, but then it just becomes a race for who happens to get the most contraband cards and that’s not very fun.

Thoughts?