Please see the pseudo-release section of http://musicbrainz.org/release-group/ad263ed1-3e94-3fa6-88bf-63d575611bb2

Date, country, label, first cat# and barcode of all six releases are identical, but the releases are not sorted by title, second cat#, or release ID either. However, they're always in that order.

If there's a logic behind this, maybe we should indicate to the user/editor what that logic is.