While working in law enforcement as a K9 officer we normally use German or Dutch commands to tell our dogs what to do. Many people believe that this is done so that others will not be able to "call off" the dog from doing what we tell them to do. While this may have some truth to it, I found that most people I had to deal with knew all the commands as well as I did. Kind of like the 10 codes we used over the radio. The main reason for the different command languages is that historically LE agencies got their dogs from German or Dutch-speaking areas and it simply became standard practice, it also sounds really neat yelling commands in German, such a harsh language.
For the dog language doesn't matter. Dougal has a mix of commands Gaelic, English, and a smattering of German. Some of my commands make no sense to the human ear, I use "Six" to tell Dougal to watch behind me (the Vets out there will understand). They just know the word(s) they were trained to. The same goes for their name.
Now, I better put my disclaimer about this up. However you want to refer to your service dog in public is fine, I am not going to say one way is better than another these are simply my thoughts on the subject.
Most people that use a secondary name for their dog in public do so with the thought that doing so will help the dog not focus on the person (non-handler) calling to the dog. This makes sense on the surface to help the dog with its focus on the handler. The way my brain works it out though if the handler uses that secondary name constantly in public, how soon will it take that the dog actually associates that secondary name to itself? Then that secondary name becomes one of the names he associates to itself, so you really have done nothing except give it a second name. Kind of like Dougal answering to Dumba$$ or Knothead.
Now, if you are changing that secondary name every time you are out in public it would negate my argument above.
