Thomas Jefferson and John Adams both died the same day.

The 4th of July, 50 years after 1776.

"Is it the Fourth?" - Jefferson's last words.

Adams' were 'Thomas Jefferson still survives', even though Jefferson had died hours before.

I smell a replacement for the birthday problem in introductory probability courses.

Absolutely. A century has around 36500 days. If you compose a list of 100 people who died on that century, your chances of hitting the same day more than once are estimated at almost 13%. As a matter of fact, even 28 people will get you over the 1%.

A problem to prepare talented probability students for the realities of the kinds of probabilities actuaries actually calculate for a living...

A search engine tells me that Cervantes died on April 22nd and Shakespeare died on the 23rd (1616).

It's even worse than that... According to Wikipedia:

"Spain had adopted the Gregorian calendar in 1582, but England was still using the Julian calendar. Shakespeare's death on 23 April 1616 (Julian) was equivalent to 3 May 1616 (Gregorian). This was 10 days after Cervantes was buried and 11 days after he died."

It's still an astonishing near-coincidence and I'm glad that you mentioned it.

To paraphrase Borges, they should have died on the same day.

forgive my ignorance, but what is the Borges' sentence being rephrased?

One of Shakespeare's lost works, a collaboration with John Fletcher, was the History of Cardenio which is believed to have been based on a section of Don Quixote.

Don Quixote was quite popular in English so it's kind of exciting to think of Shakespeare reading Don Quixote.

You gotta admit, that's better than the other way 'round.