Robert, this is a little complicated, but I assure you it is legitimate: In German, a pigeon is known as a Taube. A person who keeps pigeons is a Taeuber, where "ae" represents the letter "a" with two dots (an umlaut) over it -- I can't type umlauts on this keyboard, and "ae" is the accepted way to represent it without an umlaut. Anyway, the standard German pronunciation of this word sounds like "TOY-bear." But our Palatine and Northern Alsatian ancestors didn't pronounce it that way in their dialect. They often said the T like a D, the "oy" like "eye", the "b" like a "v", and sometimes added a "t" to the end of names ending in "-er". If you apply all of these modifications at the same time, Taeuber becomes Deivert ("DYE-vairt"). But that is the most extreme case. There are all sorts of lesser modifications: Deiver, Deiber, Deibert, Tauber, Dauber, etc etc etc. These are all just variations of the same last name. Deibert is the most common variation in eastern Pa. Ask any German language expert who also has knowledge of the regional dialects from which Pennsylvania German is derived, and he/she will confirm this explanation.
As for d'Auber, that may be another source of the Dauber name, so I can't rule out that explanation. But I should also explain that the population and language of the Northern Alsace was German. This area was a southern extension of the Palatinate, as far as culture was concerned. The French have grabbed the region at various times in its history, most recently at the end of WW2. For the sake of European peace and harmony, Germany no longer asserts its rightful claim to the area, and the French have assigned French names to many towns and gone a long way toward eradicating the authentic culture. But that still doesn't make it a French region. My Wirth ancestors came from the Northern Alsace, too, and they were hard-core Pennsylvania German. I hope this helps!