I don’t know a family personally that has siblings with identical names. But I know of some anecdotally, and the phenomenon occasionally appears in the news or discussion forums for one reason or another. George Foreman famously has five sons named George (‘so they would always have something in common’). In my culture it’s unusual, but it happens.
Toni Morrison treats this familial anomaly with comedy and flair, albeit with non-biological siblings, in her acclaimed novel Sula (1973). In Medallion, Ohio, in 1921, when Sula is eleven years old, her grandmother Eva – ‘operating on a private scheme of preference and prejudice’ – takes in three boys and disregards their given names:
They came with woollen caps and names given to them by their mothers, or grandmothers, or somebody’s best friend. Eva snatched the caps off their heads and ignored their names. She looked at the first child closely, his wrists, the shape of his head and the temperament that showed in his eyes and said, ‘Well. Look at Dewey. My my mymymy.’ When later that same year she sent for a child who kept falling down off the porch across the street, she said the same thing. Somebody said, ‘But, Miss Eva, you calls the other one Dewey.’
When the third one was brought and Eva said ‘Dewey’ again, everybody thought she had simply run out of names or that her faculties had finally softened.
‘How is anybody going to tell them apart?’ Hannah asked her.
‘What you need to tell them apart for? They’s all deweys.’
It’s as if Dewey had gone beyond the conventional function of a name (if it ever really had it, here) and become the word for a certain category of people. The first Dewey is a dewey, the second is ‘another one’, and by the third even Morrison is lowercasing them on Eva’s behalf.
When Hannah asked the question it didn’t sound very bright, because each dewey was markedly different from the other two. Dewey one was a deeply black boy with a beautiful head and the golden eyes of chronic jaundice. Dewey two was light-skinned with freckles everywhere and a head of tight red hair. Dewey three was half Mexican with chocolate skin and black bangs. Besides, they were one and two years apart in age. It was Eva saying things like, ‘Send one of them deweys out to get me some Garret, if they don’t have Garret, get Buttercup,’ or, ‘Tell them deweys to cut out that noise,’ or ‘Come here, you dewey, you,’ and ‘Send me a dewey,’ that gave Hannah’s question its weight.
In time the boys come out of their shells and accept their collective characterisation: ‘a trinity with a plural name’. They become inseparable.
When the eldest is ready for school, he refuses to go without the others. So they all go. The teacher, confronted by a motley trinity with a joint name, is ‘startled but not unbelieving’. Told they are cousins, all aged six, and all named Dewey King, she ‘gave only a tiny sigh’:
She too thought she would have no problem distinguishing among them, because they looked nothing alike, but like everyone else before her, she gradually found that she could not tell one from the other. The deweys would not allow it. They got all mixed up in her head, and finally she could not literally believe her eyes. They spoke with one voice, thought with one mind, and maintained an annoying privacy. Stouthearted, surly, and wholly unpredictable, the deweys remained a mystery not only during all their lives in Medallion but after as well.
Treating the deweys from an early age as a unity in three parts, together with their particular circumstances, seems to have led to a kind of fusing of selves – the precise nature of which is left to our imaginations. Or maybe, given Huey, Dewey, and Louie, it just goes with the name.