Not sure but I noticed this after updating from Mavericks to Yosemite DP. When I go to my contacts.app I notice on the left hand side that I have 2 sections labelled 'iCloud'.
I don't know exactly what caused this, and I can't seem to get rid of the duplicate iCloud section. Anyone else experiencing this strange issue?
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This happened to me when I upgraded to mavericks last year. If you go contact settings I bet you will see your Apple ID twice.
I cannot remember exactly how I fixed it but I first marked all the contacts I wanted and exported the v card. Do this first incase you accidentally delete all of your contacts.
I than deleted all my contacts from the contacts app and
1) turned icloud contacts off
2) signed out and back in with my apple ID.
3) tried to delete the duplicate Apple ID in contacts>preferences
After playing around with this I got the contacts app to work normal with no more duplicate sections or apple ids. Than I just imported the vCard.
Hope this sort of helps as it was the only way that worked for me.
Now everything is back to normal.