Strauss published a set of waltzes derived from the operetta; it is named "Du und Du," after the choral section of Falke's "Brüderlein und Schwesterlein" in Act II.
The set consists of an introduction, three waltzes (not the standard five), and a lengthy coda. The introduction immediately quotes "Brüderlein und Schwesterlein":
but before too long inches its way toward "Ha, welch ein Fest," the climactic dance of the Act II Finale:
The first waltz, then, offers up the two strains of that waltz:
Waltz n2 gives us Rosalinde's rebuke to the jail warden Frank in Act I and Adele's rebuke to Eisenstein from Act II.
Finally, n3 brings us two strains from "Du und Du":
In typical fashion, the coda then recapitulates several strains from the waltzes, separated by dramatic transitions.
As a point of interest, Strauss published several other pieces with material derived from Die Fledermaus: a Fledermaus-Polka, Op. 362; a Fledermaus-Quadrille, Op. 363; a polka "An der Moldau," Op. 366; and a polka-mazurka "Glücklish ist, wer vergisst!", Op. 368.
