Secretary Cam Kerry and Secretary John Kerry at the latter’s Senate confirmation hearing in January. (Linda Davidson/The Washington Post)

Commerce Department general counsel Cameron Kerry — brother of Secretary of State John Kerry — has been named acting secretary of Commerce when the outgoing acting secretary, Rebecca Blank, leaves at the end of this month.

This may be the first time ever — we’re checking — that two brothers served in the Cabinet at the same time. Of course, President John Kennedy had brother Robert as attorney general, but that’s not quite the same. (And won’t happen again because that move sparked a 1967 law, dubbed the “Bobby Kennedy law,” banning relatives of the president from getting such jobs.)

There were the Dulles brothers, Secretary of State John Foster and CIA director Allen, but the CIA wasn’t — and isn’t now — a Cabinet post. There were the Bundy brothers in the Kennedy Administration, National Security Adviser McGeorge and senior State Department official William, but neither ran a Cabinet agency.

Given the much-anticipated and likely lengthy Senate tussle over the nomination of Penny Pritzker to be Commerce secretary, Cam Kerry may be “acting” for quite some time.

So if you have the Kerrys over for dinner, be sure you specify which “Secretary Kerry ” you mean on the place cards. (Ditto at cabinet meetings.)

Meanwhile, John Kerry’s former brother-in-law, David Thorne is finishing his ambassadorial tour in Rome.