There have always been some parents who decided an unusual name they found somewhere was the perfect name for their own child. In the 19th century people didn't have movies or television to inspire them, but they did have newspapers, history books, novels, and poetry, all of which were places for them to find names.
Today the third ruler of the Rashidun Caliphate is normally called
Uthman in English, but back in 19th century his name was often spelled
Othman.
Ali was the fourth caliph, so in the 1840s
Othman Ali Abbott's parents could easily have found the two names listed next to each other in a history book. (By the way, he was born in Canada.)
https://en.wikipedia.org/wiki/Rashidun_Caliphate