SongKong contains a Year field and an Original Year field. Usually the Year field stores the year the date of the release your songs have been matched to so all songs matched to the same release would have the same value for the Year field. Then for each song the Original Year contains the date of the first release that each song was released on, but sometimes it is more interesting to know the original year than the year and this is accessible to more applications if it is stored in the Year field.
Regardless of this option the date of the album release is always stored in Album Year and the earliest release date of the Album is stored in Original Album Year