Michelle Obama attended a presentation ceremony of a Medal of Honor of Wednesday and the First Lady repeated a cherry red dress by Maria Pinto for the occasion. She debuted the frock nearly two years ago (update below) -- and has paired it with a different brooch since she first wore it.
Take a look:
In September 2009 with Dutch Princess Maxima:
The first time she wore it, thanks to commenter dual45, in November 2008: