I use the owncloud resource with multiple adressbooks. Some addresses are listed twice. In the right adressbok an a nother one. The second addressbook depends on the fist one. All addresses of one addressbook are if the are doubled in the same other addressbook. Reproducible: Always
I also use owncloud with two addressbooks. But I can not confirm this behavior. And with the little information you are giving, I have no idea what I should do to reproduce it. Did you already look in your owncloud database and confirmed that the contacts aren't stored twice?
This bug has only been reported for versions before 4.14, which have been unsupported for at least two years now. Can anyone tell if this bug still present? If noone confirms this bug for a Framework-based version of kaddressbook (version 5.0 or later, as part of KDE Applications 15.08 or later), it gets closed in about three months.
Just as announced in my last comment, I close this bug. If you encounter it again in a recent version (at least 5.0 aka 15.08), please open a new one unless it already exists. Thank you for all your input.