Well it turns out that, as seemed likely, both of them appear to have been the children of the same parents, or at least both children lived at the same address.
Sadly the first child only lived for 9 weeks, he was buried in St. Mary Magdalene ( C of E ) in Richmond in Surrey, which as you know, is the same church in which the second son was baptised.
At least that's where the funeral service was conducted, so presumably he was buried in the churchyard. The home address on the funeral record for the first son is the same as on the baptismal record for the second son.
http://en.wikipedia.org/wiki/St_Mary_Magdalene,_Richmondhttps://www.google.co.uk/maps/place/Saint+Mary+Magdalene/@51...