The German naming always listed the first name, in this case, Johann (John in english), followed by the secular name (the name used in every day life), in this case Lenhart or some variation (Leonard in english). Only one son would be called John (Johannes) and all other sons would be listed as Johann ________ (fill in the bland with the secular/every day name of Lenhart, Mathias, Georg, Wilhelm, etc).
GERMAN NAMING PATTERNS:
The custom of Germans was to give, at baptism, two names. The first was a spiritual or a saint's name in honor of a favorite saint. In my own German family, I see Johann Adam, Johann George, Johann Jacob Hetzel and some favorite female names were Anna Barbara and Anna Margaret Hetzel, all within the same family! The second or middle name was the name the person was known by within the family.
It was common practice in some German families to name the first born son after the child's paternal grandfather and the second born son after the maternal grandfather.