If i export contacts and then import them back via

Code:
/opt/zimbra/bin/zmmailbox -z -m user1 getRestURL "kontakte?fmt=tgz" > $TMPPATH/kontakte.tgz
/opt/zimbra/bin/zmmailbox -z -m user2 postRestURL "imp_kontakte?fmt=tgz&resolve=reset" $TMPPATH/kontakte.tgz
the option "&resolve=reset" does NOTHING!

i tried all of the 4 known modes and none of them does anything - every time the contacts gets doubled?!? is this only working with messages or is this a bug or am i simply doing something wrong?!?

Thanks for any help!