::::::::Sorry, Powers, you're missing the point.  Von Erck was in fact born as Phillip John Eide, and never changed his name, as he indicates on www.angrygerman.com.  He's meant to "get around to it", but never has.  He simply uses Xavier Von Erck, which is his mother's last name with a fictious first name, self-chosen, and has used this name for most purposes.  However, he has obtained an Oregon driver's ID and presumably a Social Security card using this alias. 
 Therefore, in correctly identifying Eide, both names are relevant, either by using both his correct, legal name and his chosen alias, rather than one or the other.