One of my girls does this to 3 of her long haired cage mates - she never did it when it was just her and her mum - but in a group of 6 where 3 of her cage mates are long haired she insists they must visit her salon from time to time. She loves to let them grow their hair back to a nice neat stage and then she goes ahead and gives them another very BAD haircut.
They look awful when she's been at them, but as far as i can tell they all sit there and allow her to do it - they dont seem stressed about it and when they've had enough they walk off.
My lot have a constant supply of hay/pellets and they have plenty of chew toys in their cages (they have wooden houses/steps/benches - they have cardboard boxes i frequently pick up from the supermarket, paper bags, empty loo rolls etc) - they toys are rotated to keep things interesting - so in my case it definitely not boredom or hunger. The barbering pig is also what i would class as the middle pig of the group and she was the least dominant out of all the girls when bonding - the pigs she barbers are two of the girls she's closest to and our neutered boy.
It's very annoying for me and i love my long haired piggies and my texel girl especially takes the brunt of her hairdressing skills, but she's not hurting them and so separation is the last thing i would do.
It's annoying yes - but applying sprays/lotions and so on is not a good idea - when i posted for advice, someone made a good point about the application of lotions/sprays and the fact it may deter the barbered pig from grooming/washing themselves - the last you will want is a long/semi haired pig that cannot/will not groom/wash themselves.
I know when bonding my group the screaming will be a dominance issue - my top sow was quite brutal when it came to letting everyone know she was boss and it was awful to hear and watch - eventually though things did calm down and they are all very closely bonded now.
If you only bonded them a couple of days ago, it may take some time to settle down - i would keep a close eye on them all - is the newer one being able to move around the cage freely? is she being prevented from entering hidey houses? is she being prevented from eating/drinking? is the new pig generally happy in herself?
Only you can make the decision whether to separate - for a little barbering i wouldn't, but I'm not in your situation and dont know your pigs personalities.
Good luck
