Quoting Sami Ketola <sami.ketola@dovecot.fi>:
No it does not. This is different thing. This is about managing duplicates on multiple syncs.
On 4 Sep 2018, at 18.45, Rick Romero <rick@havokmon.com> wrote:https://imapsync.lamiral.info/FAQ.d/FAQ.Duplicates.txt
Seems to use UIDs so that 'data' isn't lost.
Imapsync seems to keep track of UID -> MAIL mapping for server A and UID -> MAIL mapping for server B so that on multiple runs it does not sync the same messages again. However it does not use the same UID -> MAIL for server B as is originally on server A. And that is the problem.
That's not what you said, you said there was a client sync issue. That's definitely an issue (especially if you run Mac Mail).
Ignoring duplicates on multiples runs is a non-issue, even with the 2011 version. Recording UIDs is not necessary for that.
Rick