Oh yeah one more thing!! you need to respect the pecking order as well to avoid fights. WHen giving treats always give the dominant dog treats first, feed it first, greet it first etc.
Haha I'm not an expect but I've grown up with APBTs and read countless books on showing, schutzen (spelling?, its german attack down training), behavior etc. Its a little scary when two are in a battle for dominance. The worst thing that can happen is both are deadset in being the alpha dog. Endless fights and lots of stitches.
I know it sounds mean but if you think about it feeding, petting, greeting the sub dog second is really no big deal.