I had something similar, with calendar entries as well as some contacts being duplicated. I contacted Apple Support, and on their advice deleted my iCloud account, and all entries disappeared. I then went into iCloud on the Web via my computer, manually deleted all the duplicates there, then turned on the iCloud setting on the phone and the single, unduplicated entries reappeared.
Apparently, sometimes a "loop" happens when synching.
You should use the Windows iCloud Control Panel to set the option to sync Outlook Contacts with iCloud.
You also set this on your iPhone in the Settings app.
Once set, you won't have the option to sync your Contacts from within iTunes so there should be no further duplication.
For any contacts already duplicated, once you've done the above, just delete the duplicates in either Outlook, iCloud.com or your iPhone and they will disappear from all the other locations automatically.
As a safeguard, I always back up my Outlook Contacts to a file just in case it all goes horribly wrong
Help please !
I have an iPhone 4 and an iPad and use a PC.
I sync my contacts from my gmail account and have de-activated iCloud because of too many problems with duplicates.
I also emptied the iCloud contacts section, as well as the calendar
I manually deleted the "on my PC" group and believed everything would be ok...
It was... for a time, before I went to iTunes to refresh my safeguard !
In iTunes, I have checked the relevant box "sync the contacts with google contacts" and the "calendars with outlook".
How come that on my iPhone are 3 groups with a different number of contacts ? :
On my PC : On my PC (all)
Exchange : Contacts
Where do these contacts "on my PC" come from ?
More frustrating : when clicking on "modify" some of them have 2 "associated sheets" : "Unified" and "Exchange" , others have "Unified" and "iPhone"....
If someone could explain how to definitely get rid of this problem I would be extremely grateful !
Thanks in advance