When pianist Vassily Primakov last performed at Chandler Music Hall, his fellow pianist Natalia Lavrova was in the audience. This time around, the internationally recognized musicians appear together as the Lavrova /Primakov Duo, delivering a two-for-the-price-of-one concert of solo and collaborative pieces. The Moscow-born musicians are also longtime friends, and it shows onstage. Of their playing, Fanfare magazine notes, “Technically and tonally they are so well matched, you wouldn’t know who was on first and who was on second.” The dynamic duo delights listeners with a program of works by Schubert, Rachmaninoff and Carl Czerny.