Catalogued in RISM as “Symphonies–B♭ major; Manuscript copy; I-Rc Mss. 5748” by Anonymus. RISM 850010403
Same music
The encoded incipit, labelled Allegro, matches the Allegretto (incipit 1.2.1) of the printed symphonie concertante; the record also lists a separate Allegretto, so the label or order differs. Two solo violins fit a symphonie concertante.
Attributed copies compared (1 of 1 encoded incipit match):
1.1.1 Allegro · vl 1 · 16 of 16 pitches agree
'4.B''6{CD}4ED/GFE-/4.C8E{D'B''FD}/4.C8E4.'B{6''CD}4ED/GFE-/4.C8E{D'B''FD}/4.C8E{D'B''FD}/also RISM 1001381603 1.2.1 [p. 6, at left underneath the 11th stave:] Allegretto
also RISM 201001936 1.2.1 Allegro
Catalogue data and incipits come from RISM (Répertoire International des Sources Musicales), CC BY 4.0. Incipits are rendered with Verovio. Source and data: https://github.com/aaymeloglu/rism-attributions.