“Martin Luther” King Sr and Jr were really named Michael King. The father started using “Martin Luther” for him and his son after a trip Germany in the 1930’s. Neither the father or the son ever changed their names legally.
“...By 1934, King had become a widely respected leader of the local church. That year, he also changed his name (and that of his eldest son) from Michael King to Martin Luther King after becoming inspired during a trip to Germany by the life of Martin Luther (1483–1546)...” - Wikipedia
https://en.wikipedia.org/wiki/Martin_Luther_King,_Sr.
“Marting Luther” King Jr also plagiarized his PhD dissertation:
“...Regarding his PhD dissertation, an academic inquiry concluded in October 1991 that portions of his dissertation had been plagiarized and that he had acted improperly...” - Wikipedia
Martin Luther King, Jr. authorship issues
https://en.wikipedia.org/wiki/Martin_Luther_King,_Jr._authorship_issues