My two friends adopted puppies, they are brother and sister just shy of 6 months old, they are well socialized, get along great with my older dog (2 yrs) but get super worked up when they play together and almost always escalates in to a huge fight.. does any one know why this happens?

Sounds like they are trying to establish dominance. Cesar Millan has a great program called Dog Whisperer and he was addressing this problem just a couple of nights ago.

I've read all his books.. and I don't own a TV... so that won't help ;(