One of the things that has been bugging me since I got my 3G iPhone was that I had duplicate contacts listed. Normally this would have been a minor irritation but given that the contacts take an age to load I was keen to keep the list as small as possible. A search on Google returned lots of others who had a similar problem but none of the solutions (many of which seemed to be clutching at straws) worked.
One idea that did come up regularly was that of having multiple contact folders in Exchange but I was pretty certain that this didn’t apply to me as when I looked in Outlook I could only see a single folder. However, when I looked at the contacts in Outlook Web Access this was showing two folders – very strange. After a little digging I discovered that I did have a second contacts folder but this was in an archived personal folder, which is why is wasn’t being shown in the Contacts view in Outlook.
So I deleted this folder and waited for everything to sync-up. After a few minutes the rogue folder disappeared from OWA but the multiple contacts still appeared on the iPhone. The only way around this was to turn of contact synchronisation, wait for all the contacts to be removed, and then turn it back on again. This has, finally, sorted the problem.