I've just found a death in 1957 on behalf of a friend.
It took place at Our Lady's Hospital in Navan (An Uaimh), and the person in charge registered a group of deaths at the same time - the last four entries on the page I can see, and possibly more over the page.
However, looking at the first of this group, registered on 10 April 1957, I saw that the death actually occurred nearly a year earlier, on 28 April 1956.
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Was such a delay normal in Ireland?
For those who want to see the original on irishgenealogy.ie, look for a death of Madeline Proctor in 1957.