As a person who has their first name misspelled a lot, I should have checked this sooner. I have seen his first name spelled Phillipp, Philipp, Philip, and Phillip. I usually spell it Phillip, because that is what I am used to seeing in America. Today I decided to locate his signature to see how he spelled his first name. Ugh, I have been misspelling it.
Conrad's Stories 
So it’s Philipp? I can’t tell but that looks like it lol!
Yes, it’s Philipp. I guess the family “Americanized” the spelling to Phillip because that is how it is spelled on his tombstone!