I don't know if you have found your answer yet but I will reply anway. Better to find out twice than not find out at all.

I suggest Joseph may have been his middle name as in Germany people were usually called by their second name not their first baptized name. It is not uncommon to find 4 sons all named Johann e.g. Johann George, Johann Albert etc. The Hartcher family are linked to our family in Maitland. I have found records on the Maitland Pioneer Register for a George Joseph Hartcher who came to Australia on the Parland in 1849. He died in 1920 in Branxton and he married Elizabeth Alford in 1867 and they had nine children.

He was known as Joseph.

If you do not have his information yet please email me and I will forwarded on to you what I have.

Cathy