I have come across Duncombe as a first name. The first mention I have is Samuel Duncombe Wade (1844-after 1901) born in Dereham, Norfolk although his parents were more normally living London. He married Elizabeth (whose surname I do not have) and they had 5 sons including Zachariah Duncombe Wade and Duncombe Patrick Wade.
Samuel Duncombe Wade's parents were Zachariah Wade and Harriet (born about 1815 in Southwark, London) whose surname I do not have.
Duncombe, as a surname, does not feature in Zachariah's line but perhaps Duncombe was a surname in Harriet's line. Can anyone shed any light on this?