i have two boys as well, i get the chinning as well as little nose jabs daily since the spring/teen hormones kicked in, but they always run off after and they never bare teeth, chatter, or rise up. My dom pig is hitting his teenage hormones and this is simply boys being boys and getting a bit rowdy. They will then be seen pop corning around together or playing follow the leader and mutual butt sniffing. As long as theres no other scary signs and they disperse shortly after it should be okay. Also as much as they hide you MUST take them out for exercise. Just remove the hideys if you must to catch them or use a snuggle sack of some sort or something like that to coax them into and then be lifted. The chinning can be scary, believe me, but as long as they go about their day pleasantly they should be fine. Try to monitor them, see if they avoid each other or if you can catch perhaps some better moments. My boars will make a huge fuss jabbing noses at each other and squeaking and then immediately break out into popcorn, with my dom pig usually the first to pop! if you feel there is tension between them stuff some hay into a toilet roll or offer another simple DIY toy to distract them. If my boys have been particularly rowdy i offer each a small piece of carrot and they immediately run off to their hideys to eat it away from the other and emerge much happier afterwards