At the beginning of the episode, he's playing a part of:

Franz Schubert's Piano Sonata No. 20 in A Major, D. 959, IV. Rondo. Allegretto.

Later in the episode, he plays a duet with Roz which is:

Mozart's Concerto No. 21.

The answer is no. The Sonata for Two Pianos in D major, K. was composed for two pianos.

What now it's called Bach's sonatas for cello and piano, are the 3 sonatas for viola da gamba and harpsichord BWV 1027-1029. The second sonata, BWV 1028 is in the tonality of D major.

Short version of Franz Schubert's Piano Sonata #20 in A Major

F major.