According to us, it is highly unlikely that 
present in A was changed in FE (→GE,EE) to 
as a result of Chopin's intervention. The dynamic contrasts in bars 29-32, 33-36 and 56-60 draw on the rule of double juxtaposition of the same indications (–
or 
–). The version of A is compatible with this rule also in bars 61-64, while in FE it was broken and in a way which does not correspond to the musical flow. The engraver of FE could have simply forgotten about the 2nd .
Compare the passage in the sources »
category imprint: Differences between sources
issues: Errors in FE
notation: Verbal indications