The use of multiple names is a Hebrew tradition. Jews blended common German names with Hebrew names. Hebrew names were important for legal contracts but the ancestors that we are looking for were probably long past writing up Hebrew contracts. They were hiding their Hebrew origins and at what point they quit teaching their children Hebrew probably varied within each family. In the 1800s, it became popular in Germany, Hungary and Poland to give Jewish children local common names. It was quite common all over the world, among Jews, to take the name of a town, city, village, hamlet, etc. Just because the ancestor you're researching doesn't have a Hebrew, Yiddish or Ladino name does not mean she wasn't Jewish.
Suellen Ocean is the author of Secret Genealogy a how-to for uncovering ancient Jewish ancestry available at Amazon and B&N.