Hello CaitThorn,
Welcome to Apple Support Communities!
We want to help you get the most from your music so you can access all of your songs and remove the duplicates.
When you have multiple libraries you can use these steps to switch:
"Create or choose a library
In the Music app on your Mac, choose Music > Quit Music.
Hold down the Option key while you reopen Music.
In the window that appears, do one of the following:
Create a new library: Click Create Library.
Choose a different library: Click Choose Library.
You can name your new library (the folder containing your Music content) whatever you like. For best results, if you create additional music libraries, don’t name the new libraries “Music” or “New Music.” Make sure each library has a unique name so you’ll know which is which."
This Apple Support page has the full details: Use multiple libraries in Music on Mac - Apple Support
To remove duplicates in Apple Music, use the steps here:
"In the Music app on your Mac, click Songs in the sidebar.
Select an item, then do one of the following:
Find every instance of that item in your library: Choose File > Library > Show Duplicate Items.
Find exact duplicates: Hold down the Option key, then choose File > Library > Show Exact Duplicate Items."
We hope this helps so you can access all of your music and get rid your duplicate songs.
Cheers!
