I'll add for those curious, just as I was, that this is not the same Donatus who St. Augustine polemicizes in Ad Donatum. This Aelius Donatus was a teacher of Rhetoric, although he happens to have been the tutor of St. Jerome.
And strange coincidences with birth and death dates do happen all the time, of course. There are only 365 days in the calendar. It's well known that both John Adams and Thomas Jefferson died in their beds on Independence Day, July 4th, 1826, a few hours and several hundred miles apart. And Mark Twain was born just after Halley's comet, and wryly predicted that he would die when it came back around. He was right!