Thanks Aussie Red for the advice. He is actually getting a little better. I would almost swear he is only barking at the ones he does not like. We have only had Duke for 3 weeks and every day is better and better. We even took him to the softball park on Sunday to watch my dad play ball. He encountered at least 6 other dogs including 2 HUGE bull mastiffs and was AWESOME!! He only barked when barked at first. And then we noticed something very strange... he barked at every single person that was wearing flip flops. I certainly hope he wasn't beaten with a flip flop by his past owner. We are hoping it was just a noise issue. But, just like Dena said, it is just taking some time and effort.
My new issue is that he is scratching like mad at his upper shoulder blade area. We took off his new collar as soon as we discovered the scratching welts, because we thought the collar was irritating him. We have bathed him with flee killer shampoo and nothing seems to be making it better. I have a vet appt for next week, but does anyone have any ideas? Any suggestions on what I might be able to apply to the area to help the irritation?