Hi -
I don't have multiples, and I know they present different circumstances. I was part of a 6 child family though, so maybe I can offer some help?
Do they have their own sets of toys are are they expected to share everything? My brother and I were from one father, and there was a different father for the others. He and I had to share EVERYTHING. it was frustrating and led to some horrible fights. Eventually, my grandmother figured out that we had different personalities (go figure), different desires, different ideas, etc. She got us into different activites adn times AWAY from each other. That helped a lot. We are 5 years apart but very very close. I mean REALLY close. Everyone thinks we are twins or that he is my son lol.
As far as fighting goes, can you try separate rooms? And for hitting, with my step son - he punched me once in the face - we took EVERYTHING away from him. Toys, videos, tv, phone, you name it wwe took it. For each week he did well - we gave him a privelege back. For each DAY - one toy.
It seems drastic and it also seemed harder on us than him at first. He pitched every fit possible. He really couldn't believe we took eVERYTHING from him. He had nothing but a bed, a dresser and that was it in his room. The essentials. Then we had to tell him how we EXPECTED him to behave. Told him it's ok to be mad - emotions are fine - it's what he did because of his emotions that would be scrutinized. Hitting NOT ok. Unless - he wanted to pound the heck out of his pillow. Screaming obsenities, NOT OK. Writing out his feelings - no matter what they were - ok. It was hard on everyone.
It took about a month to get everything back. We only had to take it again once. Never a problem since. Which is a good thing since now at 17 he's 6'3 and 250 lbs of muscle. Never raised a hand to me or anyone else since. Granted he was about 7 when he did this too - so maybe it's the age.
What kind of punishment do they get when they do something like punching?