Thank you Trish. You might have solved the other mystery about George and his siblings - where is Thomas?
1605 George's father, also named George, died 21 Mar 1647 at Albury and made his will at Albury sometime between 1642 and 1647 (the day, month, year and regnal year are all blank in the PCC copy). The father's memorial stone says he had 12 children. The will names 8 - deceased eldest son John, 5 living sons George, Edward, William, Anthony and Richard and 2 married daughters (Letitia and Elizabeth). The Visitation of Surrey 1623 names an extra child - Mary, who died in 1640. The other three - Roger, Cicely and Thomas - have presumably died before 1623. I have baptisms for Roger and Cicely but no record for Thomas. Thomas is named as the 7th son in Burke's Extinct Baronetage, but no source is named. There is no room for Thomas to be born in between Cicely and Richard (the last known baptism at Shalford) so, if he was actually the 8th son, "John" at Albury would fit perfectly.
I disagree with FreeREG about the date for John's baptism at Albury. It is located between entries for 19 Apr 1618 and 25 Apr 1618, so I think the date should be 1 Feb 1617/18 and the Vicar forgot to record it at the right time. Given at least 11 weeks had passed between the baptism and the recording in the register, perhaps the Vicar got the name wrong and it should have been Thomas. There is no other record for the Thomas named by Burke. There is no other Mr George Duncomb in any Surrey register who could be the father of "John" 1618, and the elder George's memorial stone says his eldest son John did not die until 1640. The Visitation calls the father "George Duncombe of Shalford & Albury Weston in com. Surrey an attorney at law 1623". So he must have moved from Shalford to Albury sometime between Richard's baptism 26 Jul 1616 and the date in 1623 when his pedigree was recorded by the Heralds. Perhaps the baptism of "John" narrows down the date of the move.
I think the two burials for George Duncomb are the sons of 1605 George the subject of this query. The second burial is probably that of the child baptised 25 Aug 1635 at Shalford. I suspect the first burial was of a child who died shortly after birth and the parents did not have time to get him baptised.
The son George mentioned in the 1672 will of 1605 George is also a bit of a mystery. I find the will rather hard to read and cannot decide whether the son George is deceased or alive. I have been unable to find any record in the registers that would fit. Since he must be younger than the two George burials he may have been born during the Commonwealth period and so was not recorded.