When you do an exercise in pairs, people can be curious about what the other pairs have done. Ask each pair take a turn to put their solution up on the screen and spend 1-2 minutes explaining what they have done.
People like to show what they’ve done and it can help people understand there is more than one way to do things. If one pair has got much further than the others, it can serve as inspiration.
The main way this can go wrong is if a pair spends ages talking about their solution and it turns into a big discussion. As facilitator, try to curtail that gracefully and find another occasion to address any issues being raised.
Another potential pitfall is that there is too much focus on the end result and not enough on the process each pair used to get there. In most cases it’s more important how they wrote the code than the exact code they ended up with.