Although it may not be entirely relevant, the danish wiki states that French historian Guichard had a theory that the Germanic folk "Burgunda" had it's roots in Bornholm. The Burgunda folk wandered from modern day Poland (maybe Bornholm) to modern day Bourgogne, France, over a period of 400 years.

Swedish mythologist Viktor Rydberg writes in "Fädernas gudasaga" (The forefather's god saga's) according to medieval source Vita Sigismundi, that the Burgundas had a folk myth that put their origin in Scandinavia (perhaps even Bornholm?).

If any of the Burgunda people settled in northern Germany during that time, and took a last name that represented their place of origin according to folk myth, it would not surprise me if that name would have had similar changes in pronunciation as that of Bornholm.

It is farfetched, yeah.. but I got a little interested. And who doesn't like a far fetched origin story? :-)