Certainly the case sometimes, but this can only be fixed really by preventing acoustids being linked to a musicbrainzid if outside a reasonable track length (20% should more than suffice). If the MusicBrainz track really is the right one but with the one wrong track length recorded then the submitter needs to fix the issue on MusicBrainz and then submit the pairing.
In the early days of Acoustid the priority would be increasing the size of the database as quickly as possible, but now it is a more mature product should be more careful about letting data in. Since Luks doesnt seem to be round much these days the easiest way to get this done would be implement changes in Picard, what do you think about this @outsidecontext and this