Right now we require to setup two accounts if we want to sync carddav and caldav from an owncloud server. It would be much more user-friendly if both would work with an owncloud server. It actually works confusing, when davdroid says ‘select contacts to sync’ and there is nothing there. I actually searched in my owncloud setup first.
Allow syncing of owncloud carddav + caldav simultaniously under one account.
This is not related to DAVdroid but to Owncloud. DAVdroid uses WebDav Current Principal to auto-detect collections. Some people say that they only need to enter a single URL/account for OC6, I have never seen that.
Please refer to the OwnCloud support for that.