Anonymous Artist vs artist:anonymous

So these tags have existed forever and they are separated but I don’t recall the real distinction between them or if it is even necessary to keep it. The descriptions at most imply that one is mainly for 4chan artist and the latter is for the rest, but that would be a strange distinction to keep in practice and I have no idea if they are even consistantyly used like this.  
Thoughts?
 
artist:anonymous  
Anonymous Artist
 
They both have a few aliases each which just make the divide seem more arbitrary.
 
In addition, several images that have both tags.

My concern with merging them is that just because an artist posts anonymously to /mlp/ (“artist:anonymous”), it doesn’t mean that they don’t want their identity known (“anonymous artist”), though there is overlap, and it’s certainly confusing.

@Litrojia  
Indeed, from what I recall, the distinction is that “artist:anonymous” is about identifying as anon in chans, while “anonymous artist” is the generic version.