They will be okay together temporarily but you will need to separate them; the orange heads are a fairly voracious species (for roaches) and will consume the B. dubia newborn nymphs and the freshly molted individuals. They do not play well with other roaches aside from their own species and will cannibalize foreign species of insect.

With practice you will be able to identify each species - the adults will be quite obvious and the nymphs are easy to distinguish when you've seen a few of them. Smaller orange head nymphs will be slightly oblong in shape and be brown with a hint of maroon, and medium to large nymphs with be quite 'pudgy' compared to dubia and have a beautiful maroon coloration. Dubia nymphs are all fairly uniform in appearance and color being brown and having a more distinct head.

I had posted picture comparison of nymphs in this thread; all of the pictures are of Orange Heads aside from the first photo that is comparing a single orange head nymph to several B. dubia:
http://www.frogforum.net/food-feeder...n-roaches.html