If a child was illegitimate, he would be registered under his mother's maiden name. Then if the child's mother married either the child's father or another man, the child may then use the father's/step-father's name. Alternatively, if a child's father died while the child was still young and his mother remarried, the whole family may thereafter use the new husband's surname. Either way, the child could end up being known by and using either of his two surnames. In the past and particularly before about 1900, there was much less need to stick with a consistent name than there is today when we have to keep track of taxes, pensions, medical records etc.