This can be quite complicated at first.
I exported my phone contacts and imported to google.
I then indeed had two copies of each contact.
The phone linked some of them.
I thought, that if I filter the contact so only the phone ones show, I would be able to delete them, leaving the google ones.
I found that this didn't work on the linked contacts. If they are linked, even if you filter for phone contacts only, if you delete, it deletes phone and goodle entries.
I've resorted to going though each contact, unlinking, and then deleting the phone one.
Also, on contacts (such as compnaies) which don't have a first name or sir name, but use the "organisaiton field", when you re-import them from the SD card, the phone doesn't know which name to use, so takes the phone number instead.
Question : where exactly on the SD is the backup made? How can I delete it?