No Kidding!! Not sure about the Butler's, but go through any mid-late 1800's city directory, pick any moderatly common Irish surname and you're likely to find eight James' or Jas, 7 Patrick's, six Thomas', a few of Jon's and Jno's, two Mary's, an Ellen and two or three Katherine Widow of Patrick's. Oh, and no more than three of any of those people are related!
Of course, I've never dealt with any Smith's, but I bet they're fun to trace. I had a history professor in college named John Smith. After telling us his name, his first comment was, "I've still not forgiven my parents for that name."