This occurred in http://musicbrainz.org/edit/14859849

1) Start with a release that you want to change from Various Artists to multiple artists, like a split release.
2) Add the Artists using the Artist Credits field as usual, but do not uncheck the "Various Artists Release" box.
3) Proceed to the final edit pane.

See updated instructions, below.

RESULT: The edit summary (and voting window) will show only the first artist credit and the first join phrase.

(I'm not sure what the function of the Various Artist checkbox is, exactly. Is it only supposed to be used when the release actually is "Various Artists" or whenever there's more than one artist credited? If the former, why have it be separably editable – it should just key off of whether the artist is "Various Artist".)