I guess it comes down to loyalty and the PM knows the property and the local market. 

Yes, meanwhile they justify exploitative sales tactics and build backwards work cultures where loyalty is valued over good communication skills, integrity, and merit. 

"They are now scrambled with that craven crewOf angels who elected neither rebellionNor loyalty to God, but kept apart."

Later I was not satisfied with her home searching skills or Negotiation skills...I switched my Agent then the other Agent showed me a good home, we made a offer and also the sellers accepted it.Now somehow the other agent got to know it and saying that I had signed a Buyer Loyalty agreement for 1 year and harassing me to pay 2000$ to her for showing those 5 houses or else she wouldnt end the contract.

I think it also locked him into using the PM for add on lines of business like using their repair services or something similar.This shows that you value the owner's business, but you want them to show loyalty in exchange for holding them in place. 

Good negotiating skills, knowledge, flexibility and loyalty.

It is my understanding that with a dual agent (and i am the buyer) that the dual agent's duty/loyalty is to the seller, correct?  

If you really want to win an agent's loyalty compensate him something for his time, you can't put a gift in your gas tank! 

Its an "over-deliver" icing on the cake type of thing that breeds huge loyalty!

Plus I prefer meeting people face to face which establishes a relationship and possibly loyalty.