The chord featuring a 4th note, c1, is most probably a mistake in the interpretation of the manuscript committed either by Fontana in [FC] or by the engraver of FE1. In all 10 analogous places the chord played in the middle of the bar is an exact repetition of the chord from the beginning of the bar, but an octave higher. In the discussed place this rule is also observed in the A version (→GE). Determining the presence of a middle note of a chord written on a ledger line is a frequent issue when interpreting Chopinesque autographs (this also applies to Fontana's copies).
Compare the passage in the sources»
category imprint: Differences between sources
issues: Errors in FE, Uncertain notes on ledger lines
notation: Pitch