Is this date and error usual?? [solved]

Hi, I have this note in my collection, i just noticed that in Numista there's not this specific date (9 - September - 1988) but i noticed too that there's a gramatical error in the date, because (in spanish) September is “Septiembre”, and in the note it says “Setiembre”, so can anyone tell me if this is normal??, and if not aproximatelly how much it costs?.

Thank You!

Not unusual and not an error. Please remember that the Numista banknote catalog is a work in progress and incomplete. To document and catalog every single day of the year a banknote was minted  would simply be impractical and cumbersome. Secondly, the way September is spelled is a regional or dialect preference.  Either spelling is technically correct and acceptable depending on the region or dialect being used.

It's an archaic form in Spanish (mostlikely how it got to Peru) and a used one in Aragones, Asturian and Leonese.