"Lightning never strikes twice in the same place” is more a statement of mathematical odds than one of scientific certainty. There are many exceptions to the rule. For example, lightning strikes the top of the Empire State Building an average of 23 times a year. People, however, very rarely get struck twice by lightning. The phrase is usually given as a metaphor meaning that an unusual event is unlikely to occur the same way more than once.
“Lightning was never known to strike twice in one place” was cited in 1830 in an anecdote and lightning and lotteries. “Lightning never strikes twice in the same place” was cited in 1851.
“Lightning may not strike twice, but tornadoes do” is a modern variation of the proverb that dates from the 1950s.
Wiktionary: lightning never strikes twice in the same place
lightning never strikes twice in the same place
1. A lucky or unusual event is unlikely to occur again in the same way.
18 June 1830, Newburyport (MA) Herald, pg. 7, col. 1:
LIGHTNING AND LOTTERIES, ONCE MORE. A few days since a respectable young man in this town, among thousands and thousands who had drawn blanks, blanks, blanks, drew a prize of five hundred dollars. His friends, we have no doubt, trembled for the consequences, lest it should lead him to dabble in lotteries till he was ruined. We were pleased however the other day to hear him remark that on drawing the prize, he immediately came to the resolution never to purchase another ticket! and the reason which he gave pleased us still more. “He had heard folks say, that lightning was never known to strike twice in one place.” Portland Courier.
23 April 1851, The Evening Post (New York, NY), “Cost of Information Concerning the Banks,” pg. 1, col. 7:
As lightning never strikes twice in the same place, so great bank revulsions seem to be never produced twice by the same combinations of circumstance.
9 July 1851, The Democratic Sentinel and Harrison County Farmer (Cadiz, OH), “Clippings,” pg. 1, col. 6:
Lightning never strikes twice in the same place—therefore, let a man whose first wife was a good one, never marry again.
22 September 1854, Schenectady (NY) Reflector, “The Age of Letters,” pg. 2, col. 4:
... it was emphatic disproval of the adage: “Lightning never strikes twice in the same place.”
6 April 1855, Cleveland (OH) Leader, pg. 3, col. 2:
Lightning rarely strikes twice in the same place, and the same trick will not be apt to succeed soon again.
6 September 1856, Daily Illinois State Journal (Springfield, IL), “Speaking of Lightning,” pg. 2, col. 4:
Some people imagine that lightning, like good luck, seldom strikes twice in the same place.—That is a mistake.