Machines (Sweden vs. Russia)

So i got tothe city of Boo and made it to a bear by church, next thing i hear is gun fire from both Russian and Swedish Machines. Thing is, is it common for the two to be fighting against each other without player intervention or is it a bug? Ive encountered this several times in this area. Reamaing stationed at Boo for a while.

Definitely not a bug.

Without getting into spoilers, yes they are supposed to fight each other on sight.

They do get quite keen about it too. Onlookers get an automatic invite.