I just got a second guinea pig and I'm curious as to this behavior?

This is all very normal guinea pig talk for who is going to be boss of this cage, they understand it well. They are actually getting along quite well. What you will have to watch closely though is the food sharing, you should put in two bowls and watch very closely to make sure the new guy gets his fair amount of veggies as that is another sign of dominance.Actually that is the biggest problems i have had with two to the point i had to separate Miya and Suzzi as Miya just did not allow Suzzi to eat enough and she actually lost weight,