When I go to the "stars given" page, I find the following statement:
You've given 1947 stars to 825 reviews by 492 users
This seems to imply that one user can give more than one star to each review. But I think what may have happened is that the wording has been taken over from the "stars received page" even though it doesn't quite match, and that what may really be meant is the following:
You've given 1947 stars to reviews of 825 movies by 492 users