Larry Summers never ceases to amaze. Not only can he manage a huge load of outside activities on the one day a week Harvard allows professors for consulting, he can teach two different undergraduate courses that meet at the same hour! Summers is scheduled to teach both Ec 1400 (The Future of Globalization) and Ec 1420 (American Economic Policy) in the spring, one meeting MW 10-11:30 and the other meeting MWF 10-11. How will he manage? Both courses are co-taught. Maybe he will alternate, or attend one only for its Friday meetings.
For students, there is a rule against enrolling in two courses that meet at the same time like this. If it is not a typo, this would not be the first time that the faculty does not hold itself to the same standard it applies to students. But as usual, the real question is not what the rules say; it's whether it would be OK if we all did it. (Summers is also co-teaching a seminar in the spring at the Kennedy and Law Schools. He seems not to be teaching in the fall. Of course this may all be moot if he is appointed to direct the Fed, though who knows -- given his track record, maybe he can do all these things simultaneously!)