I found the following story in Judith Schneid Lewis's In the Family Way: Childbearing in the British Aristocracy 1760-1860.
I had once heard that 90% of men in Regency England were named one of four things: Thomas, William, George, and Charles. The remaining 10% were filled with Fredericks, Edwards, Roberts, Benjamins, Johns, and Alfreds.
I know it was the same for women. 18th- and early 19th-century books were CHOCKABLOCK full of Carolines, Charlottes, Emilys, Amelias, and Augustas. It actually makes it slightly miserable if you're reading a bunch of early 19th-century books in a row and are trying to remember which character was which, two books ago.
Names didn't start getting more inventive until after the Romatic movement and into the Victorian era. Needless to say, until then, it wasn't a very inventive time for naming.
What I didn't realize was that especially in the 18th century, children really weren't individualized. Since infant and childhood mortality rates were so high, why bother naming your kids something different? Give them all the same first name and then when they're old enough to be real people, call them by their middle name.
For example, the "Duchess of Leinster (1731-1814) had been quite shameless about the practice, though one might forgive a mother of twenty-one for running out of new names. She had two Georges, two Carolines, and two surviving Emilys: the Emilys had different fathers, however. Emily was her own name as well" (65).
"In the next generation Lady Holland (1771-1845) and Lady Elizabeth Foster (1757-1824) each gave two surviving sons of different fathers the same first name. The paucity of available names can easily be seen in Lady Elizabeth's case: two of her three sons were named Augustus" (65).
In one of my very, very first posts on this blog, I talked about William Cavendish, 5th Duke of Portland (1800-1879). You can tell his parents still very much subscribed to this method of naming, since he and his three brothers were all named William.