Linking contacts produces 'unknown' entries

[Christoph <crazzyman2526 gmx de>]

Hi guys,
at the moment I use an owncloud adress book and access it with
evolution/gnome-contacts through GOA, which recently received owncloud
integration.
I also like the feature to link contacts between empathy/gnome-contacts,
but it seems, that every time I link two contacts a new 'Unknown' entry
is created in my adress book containing the additional information. In
gnome-contacts I see only the main contact with the additional
information listed, so I suppose that the link process itself works
correctly.
My question now is, if this is intended behavior, as it is not really
nice to have this 'unknown' entries, if you access your adress book with
anything other than gnome-contacts? So far my only solution is to stop
linking contacts to avoid additional 'unknown' entries in my adressbook.

Any help/information appreciated
Christoph