Moses and Exodus 47

Everyone knows that the Ten Commandments were written on two stone tablets. If nothing else, most of us have seen Charlton Heston as Moses descending Mt. Sinai with those stone tablets in his hands! The question is: "Why two tablets?" If you review some classical art and re-watch the movie, you might think that each stone tablet had five Commandments each. But that is not it. Both tablets had all ten. Why were there two exact copies? And what kind of punishment did Moses mete out to the people who were worshipping the gold calf? Yuck!