According to German media, DrWindows reveals that Microsoft is about to tweak the way it calculates image space usage for albums in OneDrive cloud drives on October 16, which could result in double or multiple space usage.

In an email, Microsoft said that images saved to Gallery and Albums will be calculated differently, meaning that the same image will take up at least twice as much space.
OneDrive’s Gallery will automatically include all photos uploaded to the cloud by the user, so deleting a photo in the Gallery will result in the deletion of the photo in the Album.
After the October 16th effective date, users will be automatically included in the Gallery after uploading images. If the same picture appears in multiple albums, the space consumption of these pictures will be counted multiple times, just after the Gallery is deleted, the album can be unaffected.