Catalogued in RISM as “Le Feste d'Iside (Excerpts); Manuscript copy; GB-Lbl Add. 15990” by Anonymus. RISM 806426376
Same musicTitle already names the work
The recitative 'Coraggio anima mia' and the duet 'Deh se m'ami' match, with the same words, the Nasolini scene and duet whose title on the source is 'Nelle Feste d'Iside' (incipits 1.1.1 and 1.2.2 of RISM 850601495, catalogued there under the other title, Il Sesostri).
Attributed copies compared (2 of 3 encoded incipits match):
1.1.1 Adagio Maestoso · T · “Cara nel tuo sembiante” · no matching incipit among the attributed copies
'=/2.D,8B'G/4D2C,{8AF}/4G(G)No encoded incipit matches this one.
1.2.1 · S · “Coraggio anima mia” · 7 of 8 pitches agree
'2-4-8.-6G/BB8-B6AB8GG6-''DDC/'8BB2-4-8.-'6G/6BB8-8B6AB8GG6-''6DDC1.3.1 Duetto. Larghetto · S · “Deh sè m'ami in tal momento” · 10 of 11 pitches agree
''=4/4-8--ED/4C8E'B''6{ED}{'BG}/4B8A=4/4-8--''8ED/4C8E'8B{''6ED}{'6BG}/4BCatalogue 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.