Different name definitely! You don't want to be confused with anyone else. What about your mother's maiden name? Or using Frances with your second name and your maiden name - like Elizabeth Jane Howard (who was called Jane by her friends). Is it actually important to you that you use your own name?
As far as your title is concerned, though there's no copyright in titles a distinctive one is best. That way you come up top in search engines and on Amazon. As a new author I wouldn't go for a title that's used by several books on Amazon.
Do you have a nickname or similar? Or you could call yourself "the other Francis Harrison"? There was, yonks ago, a documentary on Channel 4 entitled "the real Graham Greene" - full of people called Graham Greene, including a fairly well known author! A friend of my wife's was on it and put forward a v. good argument as to why he was the real Graham Greene. Can't remember now what the argument was though...
You have a good name but it would be confusing if there is already a successful authorout there using it. Can you use your maiden name? It is difficult enough to stand out from the crowd and be noticed so maybe this is the chance to be creative and choose a name you find really attractive or quirky - book title too. I have spent ages agonising over a title for my first novel.
Good luck, I hope your feed back is encouraging.