In our workflow, we commit changes to a feature branch which is sometimes rebased onto master in order to keep up with the latest changes. If we push this rebased branch, all commits with references such as 'closes TXXX' or 'ref TXXX' get new commit IDs and are treated as new commits by Phabricator.
As a result of this, some of our maniphest tasks have huge lists of related commits and people get lots of notification emails.
To improve this situation, an option would be to ignore the commit ID and make Phabricator hash the changes/author/message/etcetera. I don't know if this is feasible or if other solutions are more efficient though.