By george dwarves are british, i think

[Guinevere]

so one could argue that dwarves speak anglo-saxon as ther secret language...right?

No, Anglo-Saxon is the language spoken by the Rohirrim! Or rather, just as Tolkien used modern English to "translate" Westron , he used Old English to "translate" the language of the Rohirrim. ("Westu Théoden hal!" etc)

The "outward" names of the Dwarves are of old Norse origin. I don't think their "secret language" is like any real language. It is invented by Tolkien, as are the Elven languages, but there are only a few words like "Baruk Khazad! Khazad ai menû!" What does that sound like ?