The version of A featuring b1 must be Chopin's mistake, which in this case could be explained by score-like thinking – in the voice of the 2nd clarinet implementing the bottom line of the semiquavers, a 
restoring b
is unnecessary. The accidental, present in AsI, was then added already in the stage of proofreading GE (→FE,EE), perhaps by Chopin. It is the engraver of FESB that is to blame for the absence of this accidental in this edition.
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category imprint: Differences between sources
issues: Omissions to cancel alteration, GE revisions, Errors of A, Authentic corrections of GE,
notation: Pitch