Despite the difference in forename, these records relate to the same person.
Foster: s. S., of Kingsthorp, Northants, gent. Christ Church, matric. 4 April, 1674, aged 17; B.A. 1677, M.A. 1680, B.D. 1692, a minor canon of St. Paul's 1692, sacrist 1698-1702, rector of St. Helen's Bishopsgate 1701, and of St. Michael's Queenhithe 1713; died on College Hill 16 Feb., 1738-9. Rawl. ii. 228, xvi. 112; Foster's Index Eccl.; & D.N.B. [5]
See ODNB: Estwick, Sampson (1656/71739), musician and Church of England clergyman.