It is my experience, with a substantial amount of research, that Irish children were not endowed with middle names while in Ireland, but a lot of children of immigrants to America had them provided once here. Sometimes, even if the child was born without one in Ireland, they ended up with one after living in America. No baptismal records that I've seen on the site of the National Library of Ireland have middle names. It would be good if someone who's actually IN Ireland would respond to this question so, for now, you'll have to rely on my research for a possible answer. I have many examples in my family of what I've described above.