I would check to see how you are syncing your contacts, are you syncing with iTunes AND iCloud? or possibly also Outlook? This is generally how you get multiple duplicates of the same contacts.
see these articles:
http://support.apple.com/kb/TS4147- Resolving Duplicate contacts after setting up iCloud
http://support.apple.com/kb/TS3998 - TS iCloud Contacts
for outlook users:
http://office.microsoft.com/en-us/outlook-help/resolve-or-delete-duplicate-conta cts-HP010098541.aspx - resolving duplicate contacts
I just upgraded (belatedly) to Mountain Lion on my Mac and synced with my new iPhone 4s.... I started with 4,984 clean contacts in AddressBook . . . After sync now I have over 8,000!!!! I've read in another blog that Apple is "deprecating" the sync function in iTunes in later versions of the iOS (Mountain Lion) and moving all sync funtions to iCloud... Time to go back to Microsoft if Apple won't support their own products.
I am syncing ONLY with Outlook contact, which does NOT have any duplicates.
Iphone 3GS running 6.1
-Settings->iCloud->Contacts = OFF (all are OFF except for FindMyIphone)
-Settings->Mail,Contacts, Calendars->iCloud->Contacts = OFF (all are OFF except for FindMyIphone)
-Settings->Mail,Contacts, Calendars->(any gmail account) N/A (My email are all from gmail, and none of them have contacts, just Mail, Calendars,Notes,Archive Messages)
I do not use facebook, twitter, or any other social media.
Here's what I did do...
1) Start fresh with a BLANK iphone contact list. via
- in Outlook, create an empty contact folder, 'Contacts MyEmpty'
- in iTunes, sync ONLY that empty contact folder via (a) select 'Sync Contacts with Outlook', (b) select 'Selected groups' and 'Contacts MyEmpty', (c) Advanced section, select 'Replace information on this iPhone' and Contacts
Confirm iphone 3GS contacts are empty (no contacts).
2) Now update contacts via iTunes and Outlook
-in iTunes, (a) select 'Sync Contacts with Outlook', (b) select 'Selected groups' and 'Contacts MyMobile', (c) Advanced section, select 'Replace information on this iPhone' and Contacts
My contacts now appear in iPhone 3GS, but there are some duplicates. When i look at a duplicate, for example, 'Bank of America', the only data in the contact details is the phone number (which is also identical).
any ideas greatly appreciated!