What's with the doubles?

In reading Lolita and going over it in class, the idea of a doppelganger came up very often (Humbert Humbert, 1919, Vannessa Van Ness, etc.). I wondered why Nabokov even bothered putting all of these seemingly irrelevant and insignificant doubles in. It did not move the story forward, offer any insight into the mind of Humbert Humbert (except for maybe his pretention), or really have any impact on the story whatsoever.

However, after researching why he would use doppelgangers, I found out the context of the allusion. In German folklore, doppelgangers are usually meant to represent evil, danger, illness, and death.

What does this mean in context of Lolita? What is it saying about Humbert Humbert if his own name is meant to portray evil? I think that Nabokov, although he wrote a story in which the reader is supposed to sympathize with the pedophile, is subtly putting his own opinions into the story. In the beginning of the book, we said in class that it’s hard to believe that Nabokov is not Humbert Humbert, but maybe with the use of doppelgangers we can see that Nabokov is against everything that Humbert is doing, and we are supposed to think of him as an evil human being, rather than a misunderstood man in love.