Questions about some notes in Ballade 4 Chopin

[confuter]

It occurs to me that there are some errors in the fourth ballade of Chopin or maybe I'm just stupid, anyway I'd like to know why some notes are being canceled that were never flattened or sharpened. See for example (if you've got the sheets) the third line, fifth page, second meter. There are actually multiple canceled notes that do nothing. And the ballade is full of them, is this free for interpretation or just an error?
Another thing I don't understand is that there is a note at the 8th page, 2nd meter, that should be played by both hands. The same note! Why is that? There is only room for one finger!

[stevebob]

Without seeing a scan of what you're describing (or, possibly, knowing which edition you're using), I couldn't give a definitive answer to your first question.  Different editions can be predicted to have different layouts (i.e., the number of measures in each system, the number of systems per page, etc.), and consequently the overall number of pages will frequently vary from one edition to another; for that reason, it's customary to use measure numbers when referring to the musical content at a specific point of a passage.

I am guessing, though, that the naturals you're seeing are canceling accidentals in the previous measure (or even the measure prior to that one).  Such "courtesy accidentals" aren't strictly required by conventional rules of notation, but instead may be included at the discretion of an editor simply as a reminder to the performer.

Your second question is one that is asked frequently.  I can't address the specific example you mention (for the reason stated above), but here's a recent discussion about the topic:

Same note in right and left hand?

[confuter]

Ah sorry, I thought that wasn't necessary since I am using the sheets from this website, however see for example the 73th measure. There is a 'G' 'canceled' in the RH, it was flattened in the measure before though so I guess it's indeed as you said.
Thank you for your help!