While looking for info on my gggrand Dennis Leahy, I came across a passenger list for the "Colonist" arriving New York 1/23/1851.
There were a Dennis, age 32, (which would be an age match for my Dennis as well as the time of crossing); Patrick, 30 and Rose, 18, all spelled Lahey. I understand there are two distinct lines, but it is also very easy to transpose the "e" and the "h" particularly if you are not Irish and unaware of the distinction. I have seen my grandfather's and other Leahy relatives' names mispelled on censuses, newspaper articles, etc. So it pays to keep an open mind when researching.
btw, if someone has a link to these Laheys I would love to hear from them, just to rule out the possibility that it is a misspelling.