Hi Sarah, welcome to the forum!
We're happy to have you and hopefully we'll be able to provide you with the information you're looking for. I don't know if having Rotties and Dobes is similar to owning multiple PB dogs (only because I have zero experience with those breeds), but with PB type dogs it can be a little different than you probably expect. I'm sure you're well aware of their past, it's important to know that they were breed for so long to be fighters that some may still have that instinct. There is nothing wrong with your dogs if they do display that sort of behavior-it just means you'll have to up your management skills. If your dogs decide that they don't like other dogs (or each other) you'll need to be very aware (of them and their surroundings).
DA (dog aggression) or AA (animal aggression) are common and acceptable traits in the breeds of dog that fall under the "Pit Bull" umbrella. HA (human aggression) is not and if you have an HA dog most people will encourage euthanasia.
Be sure to look around and read the stickies.