I believe that the infant Edward Bovey who died at Biscovey in St. Blazey Parish and was buried at the St. Blazey church was the son of George and Elizabeth (nee Collum) Bovey and NOT of Matthew Thomas and Jenepher (nee Dusto) Bovey.
There is only a burial record for the infant, with no baptism record. He was buried 10 Feb 1816, with his abode shown as Biscovey. Since both couples lived at Biscovey, the location provides no discriminant.
However, Matthew and Jenepher had a child Jenepher baptized 15 Oct 1815 at St. Blazey, so that it is unlikely that Edward would have been baptized by them only 4 months later. She was apparently their last child, since no further baptisms for children of Matthew and Jenepher appear in the parish registers.
There is a gap in the baptisms of  George and Elizabeth's children for the period when Edward was born and died. Charles was baptized at St. Blazey 2 Oct 1814, and Eliza was baptized at St. Blazey 19 Jan 1817.