It would appear to me that Sarah and Laura are two different people.
Sarah is 17 and in the family of Bryant Wright in 1880 and Laura is 19 and married to Willis in 1880. You have the right Wright family because in 1900, living next to Ruben is Ananias who is Ruben's and Laura's younger brother. Ananias is listed as a son of Bryant in 1880. You are on the right track.

Dont let the places of birth throw you off. Places of birth in these censuses are often wrong.

Tony