Joseph was seduced by the wife of Potiphar (Gen 39).
Later he would be married with a daughter of Potiphera priest of On (Gen 41.45).
One more reason to love the book of Genesis.
Anyway, the name variants should be common enough in Egypt, since both of them contained -r from the word Ra, the sun god, a major deity in ancient Egypt. It’s like the y- variants in Israel (Judah, Jonathan, Joel, Joseph, John, Jesus, etc.), taken from the word YHWH. Or, the -llah variants for Moslems (Abdullah, Nasrallah, Syaifullah, Hamidullah, etc.), taken from the word Allah. Similar principle lies behind such practices: the parents expect the god that they worship to to bless the child in one way or another. And that’s where the variants coming in (Potiphar/Potiphera itself means ‘he whom Ra gave’).