Topic: Who should be defined as an artist?
I think that this problem touch at least the works of Kaczmarski.
He was the singer while in some of his performance other artist have played on instruments:
- Łapiński: Krzyk (The Scream), Sarmatia (Sarmatianland? Untransable?), Szukamy Stajenki (We Seek The Stable?)
- Łapiński & Gintrowski: Mury (Walls), Raj (Paradise), Muzeum (Museum), Wojna Postu Z Karnawałem (The War between Carnival and Lent)
Hence in the MusicBrainz there is 3 different artists. To make it worst Mury and Raj are labeled as "Kaczmarski" despite being produces by trio.
What is better solution:
- Merge them into one artist - "Kaczmarski" - possibly aliased as duo and trio (my favourite)
- Move each track where it belongs maintaining 3 artists.
 It is possible that the disk was recorded many times with different artists - which only make it worst.