The MIT article was submitted earlier. The Rice submission even emphasizes that by ending with "too".

So by the time I scroll down far enough to see the Sal@Rice article I am thinking, yeah I already know he's giving a commencement address soon, and having him deliver it twice doesn't make it much more interesting.

Basically, Sal@Rice could have been the top comment on the Sal@MIT article, instead of a separate submission.

Edit: Sal@Rice currently represents comments 2, 4, and 5 on the Sal@MIT submission. Also, Sal was an undergraduate at MIT.