There are rules against double-touching
"As fierce as the competition can be, curling has a quiet camaraderie even though there have been scandals (see: Broomgate, a sweeping-related headache that World Curling believes it solved last June). So it sticks out when there are allegations of cheating."
https://apnews.com/article/winter-olympics-curling-controversy-8b7acc54e259344fb3fcfa68343af5ec