Well, almost. The conductor Kent Tritle leads back-to-back performances of the "Messiah." The first, with the venerable Oratorio Society of New York, is given in Mozart's arrangement, and stars Leslie Fagan, Sara Murphy, Nicholas Phan and Matt Boehler. Mr. Boehler also sings the bass part in the second performance, with Musica Sacra, and the vocalists Kathryn Lewek, Christopher Ainslie and Mingjie Lei.