2-c3 in 
Both the sixth present in A and the c2-c3 octave in GE1 (→FE) are almost certainly mistakes – cf. analogous bar 15. In A Chopin wrote one ledger line too little (errors in the number of ledger lines are – except for accidentals – definitely the most frequent type of his pitch errors), whereas the change in GE1 may be explained by an editorial revision, a misunderstanding at the time of proofreading or a common mistake. Chopin wrote the correct text in all three pupils' copies. The version of EE and GE2 are most probably revisions, introduced on the basis of comparison with analogous bar 15.
Compare the passage in the sources »
category imprint: Differences between sources; Corrections & alterations
issues: Annotations in teaching copies, Annotations in FED, Terzverschreibung error, GE revisions, Errors in the number of ledger lines, Errors of A, Annotations in FES, Annotations in FEJ
notation: Pitch