Op. 2, Variations in B♭ major
Op. 10, 12 Etudes
Op. 11, Concerto in E minor
Op. 21, Concerto in F minor
Op. 22, Polonaise in E♭ major
Op. 24, 4 Mazurkas
Op. 25, 12 Etudes
Op. 26, 2 Polonaises
Op. 27, 2 Nocturnes
Op. 28, 24 Preludes
Op. 30, 4 Mazurkas
Op. 35, Sonata in B♭ minor
Op. 50, 3 Mazurkas
Op. 63, 3 Mazurkas
Op. 64, 3 Waltzes
(Op. 4), Sonata in C minor
(Op. 4), Sonata in C minor, Mvt IV
In both bars the 
to A1 is written in A just below the stave, hence at the pitch of F or E. Chopin was probably adding these accidentals later and put them at a distance from the noteheads so that they do not blend in with the ledger lines, firmly convinced that in this context it would not lead to any misunderstanding.
Compare the passage in the sources »
category imprint: Source & stylistic information
issues: Accidental below/above the note, Inaccuracies in A
notation: Pitch
