Most likely the reason was a language barrier. My great-grandparents were speaking English as a second language and likely had no formal training in English and were likely unable to read or write and so there are many interpretations of the name.
Well, thanks to ancestry.com's search engines which search for names that "sound like" Mannino, I finally had a hit on my grandfather's birth record from the Winnebago County Vital Records collection. The name "Angelo Menini" but the birthdate fit and I know he was born in Rockford, Illinois, so I went ahead and purchased the certificate.
Bingo! I finally have it. The parents were listed as Viola Menini and Jennie Fontano. I will attach the image below. From this find, I learn a new bit of history - at the time of Angelo's birth, they lived at 424 S. Horsman, Rockford, Il- When I look on google maps there is no South Horsman Street - there is a North Horsman Street and a "Short Horsman Street" - I cannot find a house at "424" on either but Short Horsman Street appears as though there used to be lots there - so maybe buildings were torn down?
