In A b. 16 ends a line, while the 
hairpin ends quite clearly beyond the bar line. Perhaps this was the reason it was combined with the mark in b. 17-19, which resulted in one long . According to us, such an interpretation is unjustified, since in two previous lines the hairpins in A also go beyond the bar line, which is almost certainly merely an inaccuracy (cf. also the inaccurate, overlapping marks in b. 5-6 and 9). Therefore, in the main text we keep the separate marks, particularly since the latter begins only just on the 2nd beat of b. 17. It was also Fontana that did not reproduce the notation of A correctly, since he started writing the mark in b. 17 already at the beginning of the bar, but did not write its ending in b. 18-19.
Compare the passage in the sources»
category imprint: Differences between sources
issues: Scope of dynamic hairpins, FE revisions, Errors of FC, Inaccuracies in FC
notation: Articulation, Accents, Hairpins