I'm back but still double posting. I guess that's OK, though---I should get to "Sirloin" twice as fast now!
Ed, this was mentioned in another thread, but it appears that if you clean out your contact list and reload it the doubling goes away. I did that this morning and noticed that every name on the list was there twice, and deleting one automatically deleted both. I don't know if there's a way to add names straight to the list so I just sent out a bunch of PMs.
And then the "last visit time" started working, too...but I don't know if it was related or just a coincidence.