I found a likely brother to Varnum--Manley McConnel--in the 1900 census for Washington Township, Sanilac County, Michigan. The 1881 Prince Edward Island census shows that Varnum had a brother Manley about the age of the one in Sanilac.
My great Uncle John McConnell, b abt 1886 in Huron Township, Bruce County, Ontario, named of his first sons Manley. The Bruce County family (John & Catherine nee McDonald McConnel, spelled with one "l" is listed in the 1881 census for Bruce but I can't find them in 1871. John and Catherine immigrated to Alpena, Michigan, not too far from Varnum (Alcona County)--perhaps there is a tie to the Prince Edward Island McConnel(l)s.
The McConnell family probably spelled it with one "l" based upon census information .