Henry / Hartog / Hirts Mozes Ephraim - Name

First Name is currently "Henry / Hartog / Hirts"
and Middle Name is currently "Mozes"
I have seen a number of records for him, many of which I have uploaded to his profile, with some info in Overview, some info in the Timeline -- none give a middle name, none use"Hartog" or. "Hirts" -- all use Henry.
There is no documentation or explanation currently on the profile for those other names.

So
1) where do those other names come from / what documents or ?
2) The Also Known As field is currently empty -- Why put a string of choices in the First Name Field, rather than use the Also Known As field?