Most people don't think about this, but "spade work" is actually a racist term dating from when whites would refer to African-Americans as "spades." I think most modern people think of it as referring to hard garden work. Nope.
Just something to keep in mind!

I doubt it's an urban legend. Until recently, many people were not told they were adopted: it was considered something to be hidden (which, clearly, it is not considered to be anymore).
In that case, they may have been adopted to families in completely different towns, and their birth certificates would reflect that their parents are their adoptive parents and their place of birth was the town where their adoptive parents lived.

Of course, if it all worked out the way the man in this article supposes, it's probably an urban myth after all.