This bug has just afflicted me for the first time (although I have had problems with duplicate mails already). It actually happened while I was starting and stopping evolution in order to compile an unrelated bug report, #62192. To be more precise, I first noticed it immediately after the double evolution freeze and the total system freeze described there.
-- evolution bug, "Summary and folder mismatch, even after a sync" https://launchpad.net/bugs/27014 -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
