You can clean up duplicate contacts in hotmail.
Originally Posted by richv77
1 - Login to your hotmail/live mail account.
2 - Select Contacts.
3 - Select the Manage drop-down menu.
4 - Select Clean up contacts.
If your contacts are set to sync on your phone then they should eventually sync. This does take some time to complete depending on what you have your "Download new content option set to. You should set it to as items arrive, at least until you are finished updating contacts.
Make sure you have your Live ID account on your phone set to Sync your contacts. Follow the steps below to adjust the settings are just described.
On your phone do the following to setup synchronization between hotmail and your phone.
1 - Select Live mail tab
2 - Select "..." options menu.
3 - Select Settings.
4 - Select the target email account.
5 - Select Sync Settings.
6 - Check the items you want to sync with the account.
7 - Change Download new content option to as items arrive
Hope this helps.