Doubles my contact entries Rated 1 out of 5 stars

When trying to synchronize contacts between Thunderbird installations on different machines, Sync Kolab just doubles all my contact entries and then goes into suspension. The sequence is reproduced on every machine (Win XP/7) and I am forced to spend hours cleaning my address books. I have not seen it perform any useful action.

This review is for a previous version of the add-on (3.0.0).