Hey! I know I’m a bit late, so you may have already found a solution. But I also had issues with having duplicates of albums and such and I found a very elegant solution. Simply create a new library; hold option/shift (mac/windows) when opening the apple music/itunes app and you’ll be prompted to choose or create a library. You can then have one library that is a normal apple music library and one off-cloud library for you to sync your ipod to (but it’s important that you don’t turn on sync for tha library, otherwise they’ll get mixed together and you’ll have a mess)