In FE (→GE) there is a (cautionary?) 
to e
3 in the 4th quaver. This unnecessary revision (the accidental is absent in A!) most probably resulted from a misunderstanding or a mistake when correcting another error – in FE one can see here traces of removal of g3 (printed without a , necessary at this pitch). Upon seeing the octave with a only to the bottom note, the proofreader – perhaps even Chopin – could have instinctively added the other , particularly if he were just adding flats to the L.H. part. Having realised that it is a Terzverschreibung mistake, he marked a change to the pitch of the note, which the engraver implemented by moving the notehead along with the . EE did not include the superfluous accidental.
Compare the passage in the sources»
category imprint: Interpretations within context; Differences between sources; Corrections & alterations; Source & stylistic information
issues: EE revisions, Terzverschreibung error, Authentic corrections of FE, FE revisions
notation: Pitch