Among early German Jews Jacob Simon naming his son Simon Jacob was common before family names were used. The family names were usually required by government edict. I do not know how common continuing this practice with first name and middle name after a family name was adopted. Naming someone after a living father was not done by Eastern European Jews but maybe not for German Jews. Based on a German Jewish family that I researched (they occupied my house in Pittsburgh around 1890) Jacob Kaufmann named a son Karl Jacob Kaufmann. Karl Jacob named his son Karl Jacob Kaufmann Jr. Other family members used Jr. Bob Malakoff Pittsburgh PA