[...]There were two inconsistencies we found between the two copies:Measure 2, beat 2, second 16th note: First copy shows A, other teacher's copy shows B flat.Measure 4, beat 1, left hand: First copy shows C and B flat, other teacher's copy says C and A.[...]
You haven't said what editions you were comparing; that might have some considerable bearing. If one of the editions was Durand, be aware that Durand, even though they were the "official" publisher of Debussy, was/is notorious for mistakes in printing. Did you check measures 67 and 69; they should be the same as measures 2 and 4. For what it's worth, the Henle edition (Urtext) is the same as your "first copy."Regards,
I have got a reprint (by Dover) of first edition (by Fromont) and the second version is present in both measures, so I guess this is right.Best regards, Dr
[...]The original publisher was not Durand but Fromont (later Jobert). The Bärenreiter editor regards the first edition as more authoritative than later versions.