[mcv]

Do they change the data or only the representation? Several people here argued that LibreOffice preserved the original data, which would be a pretty fundamental difference in this context.

[erAck]

SEPT-2 is changed to date (that is how all major spreadsheet software works if an input is accepted as date), SEPT2 is kept as text as entered.

[erAck]

And actually it depends on the locale you work in whether SEPT is a valid month abbreviation or not.