By Bill Higgins: Spotted something unusual: In the April 2014 issue of Physics Today, two letters were published from two physicists, who are brothers, both commenting on the same article.

I doubt that has happened before.

James Benford and Gregory Benford were responding to an article on Cold War history by Frank von Hippel in the September 2013 issue. (Physics Today has always had a rather leisurely turnaround time in publishing letters.)