As reported by ListMyCDs on IRC: Work search results now have a spurious entry for each performance, in the "writers" column: https://beta.musicbrainz.org/search?query=peter+and+the+wolf&type=work&method=indexed (search server response: http://search.musicbrainz.org/ws/2/work/?query=peter+and+the+wolf)

Not sure if it is caused by a change on the part of MBS or the search server.