Hi Deborah, I have just this minute come across your post Re; Mannix/Manahan.
I have been sesarching for my Great Grandmothers family. I believe the came from Galway. Her name was Annie MINOGUE but on some of her children's certificates it has her name as MINAHAN. After reading your post it seems obvious that they are the same name only spelt differently..Where did you find the info re the same names? I have hit a brick wall with mine but this has given me hope. Thank you for your Post, Leonie.C.