The duo were on target either side of three first half strikes from hosts Solihull Moors, who clinched a narrow 3-2 success over the Pilgrims.
The match at Glades FC got off to a great start for United with Moran scoring early on, but the Pilgrims conceded three quickfire goals, with Cain adding Boston’s second with 20 minutes to play.
Boston (3-5-2): Jamie Bradley; Daniel Moulds, Billy Hodgkiss, Joe Cain; Daniel Worthington (Conor Allen 50), Alex Dempster (Karolis Andriulionis 55), Liam Moran, Jack Dykes (Scott Floyd 55), Jack McCallum; Louis Saebe, Bradley Easey.