[Zubersoft]

If you uncheck "Let Mobilesheets manage my files", then you also won't get any errors about duplicate songs. I may actually want to rethink this behavior, as even people who manage their own files and folders will want a way to import and ignore files that already exist in their library.

If you check that option now, you will have a mix of files that you managed yourself, and all future imports will be managed by MobileSheetsPro. I suggest you leave it unchecked. I will work on adding checks for duplicate files even when "Let MobileSheets Manage My Files" is turned off.