In most cases this is because the album is a compilation. The Olive ONE does support the correct display of compilations, but right now all the tracks have to be in the same album folder (when you copy it to the MY OLIVE MUSIC folder) to show up as one album only. This means they cannot be in separate sub-folders. If the tracks are all in the same album folder we will only display one album name (in the column view) and one album cover artwork (in the album cover view).
In the ALBUM COVER view please make sure you have selected the ALBUM icon on the right side. If you have selected ARTIST the compilations will show up several times as the ONE will show all albums for each artist.