I have two 14 week male litter mates (Sasha & Dimitri) who LOVE to play! But lately (as in the past week) they have been getting into full on fights where there has been blood spotted on one of their coats around the neck, and after some much needed damage control it was found that the blood was actually coming from one of their mouths like they collided teeth during the event. My question is, why is this happening? Is it just a dominance thing or is there something more happening that I'm not seeing? I've also read of a couple articles that said to let it carry through and they will sort it out themselves... but I don't think I believe that.

Erm, maybe one of them just lost a tooth? I can't see two puppies being aggressive with eachother but maybe someone else can pitch in.

Well for one, you should let them handle it on their own. I do find it is a dominance thing as they are both males, same age and from the same litter.
My female and male are a month apart, and they wrestled it out to where I would find blood on eachothers coat's too. After months of wrestling and constant battles, they were able to sort it out. The blood from the tooth was probably a bite from the other since they do use their mouths to fight. I honestly really wouldn't worry too much about it, since they are still puppies.

puppies that young i wouldnt think are being aggressive or violent toward one another, i would say that they are just playing and that a tooth got snagged. one may have just recently lost a baby tooth and that could be the blood.

they will work it out, i think if you try and get between them it would just make it take longer for them to get them selves figured out

I agree with all of the above especially the puppy thing, I dont think they know aggression yet either, definately dominance though. They will work it out.

They're only shy of four months old by two weeks, which is when they normally would start teething and loosing teeth. So I'm gonna go with someone lost tooth. When we had our meetup last month Link was teething and led all over the girls. It happens, I wouldn't worry about it. And I would let them fight it out, otherwise they're gonna continue to fight.