I think there are two Sjur Selje born in 1871, both married to a woman called Ida.
Sjur Olsen Selje is your grandfather, son of Ole Anbjørnsen and Martha Bårdsdatter.
Sjur Sjurson Selje is your grandfathers cousin. His mother is Gjertrud Bårdsdatter (sister of Martha) and his father is Sjur Kjelson.
Anne