Superstitions
It was thought that Jews of the same name should not live in the same town or permit their children to marry into each others' families; this seems to have some reference to exogamy. It is even urged that one should not marry a woman of the same name as one's mother; or that she should be required to change it. Even to the present day it is considered unlucky in Russia for a father-in-law to have the same name as the bridegroom. In other parts of Russia it is considered bad luck to name a child after a living relative. When several children have died in a family the next that is born has no name given to it, but is referred to as "Alter" (Yiddish: אלטער, literally "old"), or Alterke, the view being that the Angel of Death, not knowing the name of the child, will not be able to seize it. When such a child attains the marriageable age, a new name, generally that of one of the Patriarchs, is given to it. For a somewhat similar reason it is considered unlucky in Lithuania to call an only child by his right name.
Read more about this topic: Jewish Name