I started to use Lightroom few months ago. However I don't understand why Lightroom save twice the photos: one in with the normal method based on date (ex. 2017/05/23/photos.jpg), and another in a new folder called "Imported on" and date (ex "Imported on 23 May 2017"). Is this "Imported" folder necessary? Can I delete it? There is a way to tell to Lightroom to not create it? Thanks
Make sure that "Make a second copy to" is unchecked in the import screen. This option allows you to make a second copy of your import for backup, etc. You can delete the "Imported On" folders as they are not referenced by the Lightroom library.