Washington music lovers may have problems next Friday evening choosing between the Kennedy Center, the Library of Congress and the Shrine of the Immaculate Conception.

At the shrine at 8:30, Paul Callaway will be the soloist in three of the greatest works for organ and orchestra: the Barber Toccata Festiva, the Piston Prelude and Allergro and the Poulenc Concerto. To these, he will add two Mozart sonatas, and Daniel Pinkham's Concertino for organ and strings. Robert Shafer will conduct the orchestra.

At the same time, guitar virtuosos Julian Bream and John Williams will make one of their infrequent joint appearances in a Kennedy Center concert.And the Juilliard Quartet will add the unfamiliar name of Krommer to a program of Haydn and Beethovan at the Library of Congress.

In September of 1939, Princess Edmond de Polignac wrote to her good friend Francis Poulenc. The astonishing American-born patroness of the arts (she was born Winnaretta Singer, of the sewing machine family) began: "I do not deserve any of the sweet things you write to me. It is I who owe a great debt of appreciation to you for so many beautiful hours of music, and for having made for me the concerto of Venice and that of Paris, whose beauty haunts me." The Venice was Poulenc's concerto for two pianos; the Paris was the concerto for organ, percussion and strings which Poulenc dedicated to the princess upon its completion in 1938.

World War II had broken out on Aug. 1, 1939, and the princess was writing to Poulenc from Devon, England, where, as she continued, her family had insisted that she should go for safety's sake, "to the country to which the war of 1870 had brought me in my childhood."

Poulenc's friendship with the princess, and her interest in and support of his music, went back nearly two decades. It was in her famous Paris salon that Poulenc had first heard Wanda Landowska play the harpsichord, an experience that led to the famous performer's asking him to write a concerto for her. This, Poulenc immediately set about, dedicating the completed work to the princess in 1929.

He had anticipated that the premiere of his organ concerto would take place in that same salon, especially since the princess was expert both as pianist and organist. It turned out, however, that the first performance was given in the Salle Gaveau in June, 1939, with Maurice Durufle as soloist. It was the memory of that occassion that haunted the princess as she wrote from England.

Samuel Barber's Toccata Festiva was commissioned by Mary Curtis Bok Zimbalist to celebrate the installation in Philadelphia's Academy of Music of a superb new Aeolian-Skinner organ, also a gift of hers. Although it is little more than half the length of the Poulenc Concerto, the toccata was designed to show off not only the resources of the modern pipe organ, but also to mix and match the organ's resources with the sounds of Philadelphia's famous orchestra. Midway through the toccata, Barber placed a cadenza of fiendish difficulty in the course of which the organist is required to play chords on the pedals (solely with the feet, obviously) in the upper reaches of the pedalboard.

Callaway gave the world premiere of the Barber Toccata with Eugene Ormandy and the Philadelphians on Sept. 30, 1960. At the end of that performance, one of Philadelphia's Main Line subscribers sitting behind me turned to her companion and said, in a voice that easily carried for rows, "Hmph! That organist did not even touch half the instrument!" Everybody has to be a critic!

Paul Callaway has had a close acquaintance with all the music he will play at the shrine. Many years ago he conducted a similar program in which E. Power Biggs was the soloist at the National City Christian Church. While the Barber was at that time still some years in the future, Callaway and Biggs performed both the Piston and the Poulenc.

Piston's Prelude and Allegro was one of many works Biggs commissioned during his quarter of a century of Sunday morning concert broadcasts over the CBS network. Expertly crafted, its construction, reminiscent of a Bach prelude and fugue, produced one of the finest works of one of this country's outstanding and now unreasonably neglected composers.

The combination of Bream and Williams is something that rarely comes to any concert stage. For years the two masters of the guitar has pursued their own careers. During the long decades in which Andres Segovia has reigned as the instrument's king, both Bream and Williams have been proposed, by those who cannot resist such lures, as "crown princes."

It would be futile to try to place one ahead of the other in any imaginary race. As is always true of such great artists, each has his own genius; there is no "greatest." The remarkable fact is that, after the success of two recordings made together, Bream and Williams are making a number of joint appearances this season.

Their concert will be a bit like those rare times when Isaac Stern and Pinchas Zukerman get together of violin duos, or like that rare day when pianists Vladimir Ashkenazy and Malcolm Frager pooled their talents, or even that distant era when Ossip Gabrilowitsch and Harold Bauer did the same thing in a way no one who was fortunate enough to hear ever forgot. (Nowadays when Rudolf Serkin and Vladimir Horowitz exchange birthday greetings over the phone, they, too, often talk about "How would it be if we . . .") Now wouldn't THAT be something!