You have run into the problem which has made my research difficult in the past. There were two Blanchard families in southern Vermont and Berkshire county which both came from eastern Massachusetts but were not closely related. I am descended from both.
Isaac Blanchard (son of Lemuel and Mary (Littlefield) Blanchard) was born 26 Jun 1787 in Guilford, Windham Co., VT and died 24 Jan 1861 in Readsboro, Bennington Co., VT. He married Beulah Wilcox 25 Jan 1814 in Readsboro. I know nothing about children. this line can be traced back to the foundation emigrant Thomas. See A Blanchard Memorial in print or Ancestors of Shirley Louise Parmenter on line.
Isaac Blanchard (son of Nehemiah and Lucy (Jones) Blanchard)
was born about 1806 in Vermont perhaps in Whitingham or Guilford. He married Lydia (Stafford?). Nehemiah may be the son of Joshua and Mehitable (Brown) Blanchard. Isaac had a sister Mehitable who married a Chauncey Stafford. This Isaac lived in Adams, Florida, and Hawley, MA.