All of the pig breeders that Wooly Pigs contracts with have reported that Mangalitsa sows are very nasty to each other.
The typical story is that a sow gets pulled from the group to farrow. After weaning she's put back in with the group. At that point, the other sows will gang up on her and bite her when she tries to eat or drink - in the back legs or vulva. They'll make her sleep outside, away from them, even in very cold weather. This typically goes on for a 2-4 weeks. It is possible for the bullied sow to get maimed or die.
The various farms report that Mangalitsa pigs fight 2-4 weeks, compared to 2-4 days for regular pigs.
Pigs being fattened for slaughter do the same. Pigs will "hog" the feeder and stop newcomers from eating - even though the feeder is full of food, and allowing the strange pigs to eat wouldn't decrease the amount of food available to any pigs.
This information is from four farms, all very different from each other. It is in keeping with what I've heard from the Austrians.