In the sources, there are no accidentals before the first and last notes of the 3rd L.H. figure. Therefore, the bottom one should be interpreted as a
due to the 
in the previous figure (it is particularly clear in the notation of the sources, in which the 3rd figure is still written in the bass clef). Naturally, it is Chopin's oversight – the harmonic context requires the notes to be interpreted as a1 and a; in such a situation, the top one does not need a 
, and Chopin considered an accidental next to the bottom one superfluous in such cases (cf. b. 3-4). In the main text we add a cautionary also next to a1.
Compare the passage in the sources »
category imprint: Interpretations within context; Editorial revisions
issues: Omissions to cancel alteration, Inaccuracies in A, Errors repeated in GE, Errors repeated in FE, Errors repeated in EE
notation: Pitch