Johannes Berge

I am searching for information on my great grandfather Johannes J. Berge, who was born June 8, 1854 or 1855. He came to the U.S. in 1874 and settled in Portage County, Wisconsin in the 1880's. His death certificate lists his father as Jens. I can track him through the U.S. Census, once he settled in Portage County, Wisconsin, but I can't find anything on him in Norway. He died November 25, 1933. He married Oline abt 1885. She was adopted and I don't have her last name, but know from the census, that she was born in Wisconsin in 1857. She died in 1913. He sometimes went by either J.J. Berge or John Berge too! A great aunt once told me that Johannes was from the Vegårshei area, in Aust-Agder. I have also been told that he came over with a brother, but they separated when they reached the U.S. and never saw each other again. He worked in a saw mill when he first came to the states. My father always claimed that Johannes had told him that he changed his name when he came over. It was said that he added the "e" at the end, because there were so many Berg's coming over. I can't prove that, but my father and his older brother's always maintained that was true. This is all the information I have on him and would appreciate any help you can give. Thanks, Wanda