While digging through the non-sequential tracklists report I found a couple of releases which have each track listed twice (with the same track number):
http://musicbrainz.org/release/df92eb69-47b0-4641-959a-a81ee1f7cbc1
http://musicbrainz.org/release/ffd7df87-4e99-40e6-87d1-dc7995b5cf43
I haven't tried, but I suspect that trying to remove the duplicates would have consequences on the other tracks as well.