Knoll Births in Vermilion County, Illinois

I found the following births for the Knoll family name at the Vermilion County Courthouse in Danville, Illinois. You may contact them for more information or a record of the birth. The cost for a paper copy is $10.00.
Knoll, unnamed, sex unknown, parents Charles and Mary Knoll, born May 15, 1905
Knoll, unnamed, sex unknown, parend no father listed mother Mary, born July 1, 1909
Knoll, Alfred, male, parents Karl and Eva, born April 24, 1905
Knoll, Bert A., male, parents Karl and Elizabeth, born March 6, 1896
Knoll, Clarence J., male, parens Karl and Elizabeth, born Jan. 2, 1894
Knoll, Laura B., female, parents Charles and Eva, born March 4, 1907
Knoll, Laurence, male, parents Karl and Eva, born Feb. 8, 1901
Knoll, Martha Barbara, female, parents mother Eva Elizabeth, born Oct. 2, 1903
Knoll, Otto, male, parents Karl and Elizabeth, born Aug. 20, 1899
Knoll, Robert, male, parents Carl and Eva, born Dec. 26, 1897

I have come to the conclusion that Karl (Carl) is married to Eva Elizabeth. That sometimes she was listed as Eva and others as Elizabeth.