Do you think Glam ever legally changed his name?
I don't think he would have changed his first name, at least. He gave it to the police and it's hinted that some of the kids' teachers may know it.
But I think it's entirely possible that he changed his surname shortly after marrying Victoria. I kind of like the idea of them literally taking "Metal" as a new surname. The rationale being: It may be silly, but not as silly as "Shvagenbagen."
That would also make it more difficult for Dee to just go online and search the name.