Due to feedback from and code contribution by Lucas Treffenstädt I was able to improve ThunderSync even more.
Version 1.2 will use unique identifiers (UID) to find and handle contacts. If no UID is given, internal and external contacts are mapped using the number of matching properties and an UID is assigned afterwards. So now it is possible to manage contacts with identical names, e.g. popular ones like John Smith or Peter Müller. Name changes are possible, too.
Furthermore the UID is used as export filename. This fixes errors resulting from “wrong” (with regard to file naming conventions) contact properties.
Finally, comparison is done when the ThunderSync dialog is called — this avoids another unnecessary click on “compare.” And another configuration option was spent to define startup behaviour: now ThunderSync can be called at Thunderbird startup (code contributed by Lucas).
Stay tuned for version 1.2, which will be released in calendar week 8.