When I attach a DiscID to a tracklist and want to set the track duration via "Set track durations"-button, the edit window normally opens up.
I can enter the edit, but you aren't moved back to the overview page but instead, you see the same window again and again, you have the possibility to enter the edit which creates at least one duplicate.

This was the data for me:
http://ngs.musicbrainz.org/cdtoc/a7Z1i6BkvonXXopWkU6mhRQOXzI-/set-durations?tracklist=1082443
http://ngs.musicbrainz.org/edit/14463450
http://ngs.musicbrainz.org/edit/14463452 (the duplicate)