How do I merge contacts rather than replace them during sync conflicts?

I just got my iPhone 4 a few days ago, and the Verizon sales associate transferred the contacts from my previous phone.

Now, when attempting to sync via iTunes 10.4 (80), I'm given only three options after a sync conflict notification regarding contacts synchronizing: Sync Now, Sync Later, Review changes (or something like that): Rather than merge pre-existing Address Book contacts, it wants to override them, regardless of whatever information I already have in the Address Book, assigning the iPhone info priority (so any Address Book entries would just be overwritten).

Why is it doing this? It doesn't strike me as well-designed at all, especially since merging contacts seems a fairly common thing these days. An apparent work-around would be manually editing the ~30 contacts in Address Book, and then deleting each off my iPhone, but surely there's a better and faster way? Please help!

Thanks for reading.