E.g., I add the release by Jerry Lee Lewis with a recording "John Henry" (length 2:30).
We have in database five recordings "John Henry" by Jerry Lee Lewis with similar length:
http://musicbrainz.org/artist/b59ac58d-036e-4bba-8112-c32a34c4575b/recordings?page=35
But when I search the recording during release addition, I see in first lines (and even pages) the recordings by other artists and with completely different length (see the screenshot attached):

• Lonnie Donegan (without length)
• John Renburn (3:22 and 3:25)
• John Lee Hooker (3:11), etc.

No Jerry Lee Lewis there, no recordings with length close to 2:30.