We have observed a strange behaviour on "Modified By" column of a document library.
In our scenario; a file has been uploaded in a document library (versioning enabled). Another person opens that file in view mode and closes the file without saving. In
some specific case the "Modified By" and "Modified Date" fields are updated by this person/current date-time.
Surprisingly version history indicates only one version and by name of last person/date-time; while "Created By" field still holds the name of person who uploaded file