The presently more common name Evelyn is presumed to stem from Evelina.
During the Norman Conquest the name Aveline was introduced to Britain, and became popular during the 12th and 13th centuries.
The name accumulated many variations, resulting in the creation of surnames such as Aveling, Eveling, Eveline, Aveline, etc.
In the 18th century an English trend of preferring the latin form of women's names lead the authour Fanny Burney to name the titular character of her 1778 novel "Evelina".
The popularity of the book lead to Evelina becoming the most common version of the name up till the present day.