You can use “Merge” at the album or artist level.
Or perform the Plex Dance “lite” (omitting step 4) with both albums/artists.
If you want Plex to respect your meta tags, you need to check “Prefer local metadata” in the library properties.
But you need to be careful about the folder structure that you put your music in.
See Music artwork does not show the right one - #4 by OttoKerner
as well as How to mirror tags update to library? - #12 by OttoKerner
