Here's a duet I did not know about until today:
However, it was published in the Tecla' Sor: The Complete Works for Guitar, Volume 9.
Here's what the publisher write about it :
Brian Jeffery wrote:Although this piece survives only with parts for two guitars and nothing else and it has been published as a guitar duet, I wish to suggest that in fact it may not be simply a guitar duet but rather an accompaniment, for two guitars, to a bolero for two voices by Sor. I shall explain below why I believe that this may be so. If this hypothesis is correct, then it is historically significant because it gives us the only known authentic accompaniment for two guitars to any of Sor’s songs, and also musically interesting because it works extremely well as an accompaniment for a bolero. Also, because it has such character, and because it can easily hold its own against the voices, it can provide a model for performers of other songs by Sor who may wish to try their hand at improvising accompaniments in the style of the time. I must emphasize, however, that at this time it is only a hypothesis, and the piece may of course be played as a guitar duet by anyone who wishes to do so.
The Bolero a Duo is found in only one known source, an edition printed in Madrid between 1817 and 1824 entitled Colección selecta de musica ynstrumental para guitarra sola de los mejores autores nacionales y estrangeros. In that source it is entitled Bolero a Duo con dos guitarras compuesto por D. Fernando Sor. It is a short but lively piece as befits a bolero, full of zest and colour. It breathes the rhythmic vitality of other known pieces related to Spanish dance at this time such as Aguado’s fandango for guitar, Soler’s fandango for keyboard, Boccherini’s fandango, or indeed the other boleros of Sor for voice(s) and guitar or piano.1
There are, however, some questions about what exactly it is. Is it an original work by Sor? Or perhaps an arrangement from something else? Is it for two guitars and nothing else, or is it an accompaniment to a song? And if it is by Sor, then what date is it? We do not have many firm answers, but there are some clues.