TntMPD can sync 2-way with Outlook. When it does this, it tries to match the contacts that are in common between TntMPD and Outlook.
For the contacts that are in common, it tries to find where the change occurred. If it happened on only one side (TntMPD or Outlook) since the last sync, it will automatically be able to determine which way to propogate the change. If a change occured to the same contact on both sides, it will mark this as a "Skip" and you'll have to manually decide what to do. You can double-click on a Skip and do a side-by-side comparison of what's different for that item. In this side-by-side comparison, you can double-click on the value you want to keep for each field. You can also right-click on the "Skip" and choose a different action. At this point, it will also give you the option to "Update TntMPD Only" or "Update Outlook Only" if you want to propagate all changes in one direction unconditionally.
For the contacts that are not in common, it gives you the option to export new contacts from TntMPD to Outlook or to import new contacts from Outlook.
Before TntMPD 2.1.22, there were some shortcomings with the way TntMPD handles change detection. These shortcoming have been addressed. Please disregard any previous advice that suggest you should pick one program (TntMPD or Outlook) as the master source where you edit data. The sync feature is now updated to provide a true 2-way, peer-to-peer synchronization experience.