The difference between the USA and Germany is that we have no middle names. We only have first (or christian) names and a family name. So we can take the first name we like. And there were only a handful christian names the people had. So sometiimes people take another first name as they got by their baptism because they had siblings with all the names thes had. So they take another first name. The only way to find the correct person is to find souces with the information about the parents and with a birthday.
Another problem we have is that some people emigrated with the papers of others. I have had a member in my family living in the USA with papers of a person died as child. Therefore it was a big problem to find the right person. For my family it is easier because of my family name. If you search for such a person mith the name Meyer or Müller or maybe Kruse you will have a big problem!
Gunter Jüchter