I imported a single vcf file with multiple vCards with the gpesyncd package. Should be in the same repo with the rest of the gpe stuff.

There's a trick, naturally. Edit the vcf file and put "ADD VCARD" before every "BEGIN:VCARD".

Then import with "gpesyncd < vCard.vcf

I was able to import my Mac Address Book using this method. No way (that I know of) to do real two way synchronization.

The built-in Contacts program imported the unmodified multi-vCard file with no complaints.

The address book in claws-mail also imported the multi-vCard file (email addresses only though).