It is often called the hedgehog rut, so you chose a good nickname! Very often it goes further than head butting and one hedgehog will push the other one along (sometimes rolled up but not always) often for several yards. Often it is to do with keeping competition away from the ‘ladies’.
I always thought this sometimes looked quite aggressive, but this year, I have seen several full blown extremely aggressive fights when one hedgehog will literally be shaking the other like a terrier with a rat. I have noticed a bit of a ‘pecking order’ here in previous years, and wonder whether these fights are to do with one hog trying to move up the ‘pecking order’. They are mostly back to just biffing again now.
Hedgehogs do not have territories, as such, they are more like ranges, and these overlap. They are often thought of as quite grumpy animals, and if they meet another hedgehog they may well give it a biff. Of course, they are more likely to meet at feeding stations, so this behaviour often happens there.
