DON'T PANIC !
Haha, keep calm and carry on! My two brother piggies, Bentley and Chester, get along great, they occasionally mount each other but it's perfectly natural, well it's weird but they'd do it in the wild, it's just there behaviour, and as long as you keep an eye on them you can just leave them too it !
Eddie and Ollie are my two slightly naughty boars, they occasionally squabble but they just chase each other and then calm down, it never gets to rough because in most pairs there will a submissive one that just takes it and goes of quiet,
With my Bentley and Chester, Bentley used to be submissive but he's trying to be dominant now, and Chester is just letting him, mainly because he's to fat to care, but don't be worried, they sort everything out between themselves !
Boars aren't as terrible as they sound !