Name changes are common. I've got two in my maternal family and my wife has one. I dont think Tuerto will mind me saying that there is one in his FH. That was a devil of a problem to unpick, but we got there in the end, even solving why it had happened.
DNA testing can obviously help here to - the question to ask is if there's a match, but you don't know why, work thru the evidence.
I should add that as well as my 247 close matches, there are thousands of other matches.