after migrating a photo library and viewing it in photos, the migrated library show in Documents folder. Can I delete it? In another words was that library copied and converted for Photos and therefore is a duplicate using up my storage?
MacBook Air 13″, macOS 10.15
When you migrate an iPhoto Library or Aperture Library to Photos, the Photos.app will create a new library from it. The new library will have the filename extension "photoslibrary", the old iPhoto Library will have the extension "migratedphotolibrary". Both libraries are independent of each other. The old library does not need to be on the same volume as the new Photos Library. You can remove the old library. You may not gain as much storage back as you expect, however. Even if both libraries are showing the same size, the system is managing the storage efficiently and both libraries are sharing the storage for identical image files, while the libraries are on the same volume, so the storage for the original image files and identical previews is only used once. (https://web.archive.org/web/20190502225116/https://support.apple.com/en-us/HT204476)
I would move the older library to another volume, until you are sure, that all photos have been migrated correctly. You may need to repeat the migration or convert some files to a different format, if you should notice, that some items could not be migrated correctly.
When you migrate an iPhoto Library or Aperture Library to Photos, the Photos.app will create a new library from it. The new library will have the filename extension "photoslibrary", the old iPhoto Library will have the extension "migratedphotolibrary". Both libraries are independent of each other. The old library does not need to be on the same volume as the new Photos Library. You can remove the old library. You may not gain as much storage back as you expect, however. Even if both libraries are showing the same size, the system is managing the storage efficiently and both libraries are sharing the storage for identical image files, while the libraries are on the same volume, so the storage for the original image files and identical previews is only used once. (https://web.archive.org/web/20190502225116/https://support.apple.com/en-us/HT204476)
I would move the older library to another volume, until you are sure, that all photos have been migrated correctly. You may need to repeat the migration or convert some files to a different format, if you should notice, that some items could not be migrated correctly.
migrated library
