This is due to the use of random number generators (RNGs) that continually shuffle the deck. https://1-o.net/%ED%8C%8C%EC%9B%8C%EB%B3%BC%EA%B2%8C%EC%9E%84%EC%8B%9C%EC%9E%91-%EC%83%88%EB%A1%9C%EC%9A%B4-%EA%B8%B0%ED%9A%8C%EB%A5%BC-%EC%97%AC%EB%8A%94-%ED%98%81%EC%8B%A0%EC%A0%81%EC%9D%B8-%EA%B2%8C%EC%9E%84/