Both Gamlingay Sarah baptisms are extracted onto the IGI. I can't imagine that both the LDS AND Cambs FHS have made an identical transcription error. Could her parents have forgotten that she'd already been done, and did her again in 1812?
These William and Eleanor baptisms raise a number of questions - the first baptism was in 1794, the last in 1828. Seems too long a span. Could there have been two William & Eleanors?
In 1851 living in Gamlingay was Eleanor Meeks, 60, obviously not the mother of Sarah baptised 1799 if her age is correct, but I can't see her in 1841. And in 1841 in Gamlingay was William 77 and Ellenor 67 Meeks
In answer to your original question genuki details non-conformist churches in each Cambs parish, and Wilburton just has the Church of England
David