At some point, they will stop testing each other's boundaries. As for right now, I agree with Freckles317. As long as no blood is shed, try not to worry. Every puppy goes through this, trying to find her place in the "pack."

Did you have siblings? I remember the squabbles we human four had, and my Dad, (who was an only child) shaking his head in dismay - but we all lived to grow up, and are still friends! I bet they will be too, just give them time.