I finally took a serious look at my particular duplicate artist problem and wanted to follow up. In my case, the issue seems to be related to folder structure and albums with various artists.
Most of my music is organized by Drive\Music\Artist\Album\Tracks.mp3. It turns out I had a one big flat folder in my music directory that was a dumping ground for a bunch of tracks that I had not sorted. The majority of these tracks were rips from Billboard Top 100 collections for various years.
Some of those tracks I had re-tagged as the artist's album:
Title: The Sun Always Shines on TV
Album Artist: a-ha
Album: Hunting High and Low
Others were in the same folder from a different album artist:
Title: Take on me
Album Artist: Various Artists
Album: Billboard Top 100 of 1985
In addition to those tracks mixed in one big folder, I had other a-ha tracks from the same album under the artist folder in the main structure (Drive\Music\Artist\Album\Tracks.mp3).
Using MeidaMonkey, winamp, or other music players I never encountered duplicate artists and didn't think much of it. Now that I'm getting used to the way EMBY works, it seems like I was asking it to mix artist/album tags and folder locations and it was doing it's best to make sure it didn't leave anything out.
Long story short (too late), I finally separated the Billboard stuff and the remaining one-offs into the correct artist folders and the duplicates went away. I haven't scientifically tested what was the exact case that causes the duplicates, but if you're having trouble I would check your folder structures in addition to tags.
Note: Re-edited to correct misspelling of Ah-ha
Edited by Tremas, 24 February 2017 - 05:07 PM.