A release group may contain a releases with a different tracks' sequence and/or number. Examples:
http://musicbrainz.org/release-group/4ddf4de7-5084-36c8-990b-73a968b3f8b6
http://musicbrainz.org/release-group/4c7d5b41-50bc-404b-ae0d-e7cf8959e487
When we add a release to a release group and use a similar release as a starting point, in such cases the presence of similar release is useless: we have to add each track on tracklist (title, artist credit, length) manually as a new recording. And on the next step we have to identify each recording as a new recording (and a system's suggestions for each recording are absolutely false as attached to a track's position in the medium!).
The same problem exists when we add a missing track to an existing medium:
http://musicbrainz.org/edit/15676159
Such problems can be solved by adding of the feature of track's sorting, i.e. of changing of the tracks' position in a medium (like the existing feature of changing of the medium's position in a release).
Maybe, in view of this, the concept of forming of system's suggestions for the recording's identification should be revised.