The sheet music we're sharing here is arranged for duets of Op. 5, No. 10, for violin and viola.Viola is tuned one octave above the cello. As a result, the viola can't faithfully replicate the cello part from the original. There are notes that are too low for the viola's range. In the arrangement for violin and viola, we strive to stay true to the original notes. If the notes aren't in the viola's range, we raise them by one octave. However, following this rule too strictly can lead to unnatural sequences. In such cases, even when the note is within the viola's range, we use a note one octave higher to maintain naturalness. Additionally, in the third and fourth movements, we've swapped the solo part and basso continuo part in the repeating sections. Shifting the melody to the viola brings a fresh sound. In the audio samples below, we've used a flute sound for the violin part and a clarinet sound for the viola part. This should help you better understand how the swapping works.