I'm American and was given the name Geoffrey on my birth certificate, but so few Americans know how to pronounce it correctly (kids and even some adults said "Joffrey" and "Jee-Off-ry") that we changed it to Jeffrey and Jeff when I was a child. Even I'm a bit confused when I see the British name "Geoff" (looks like Jee-Off at first) and realize it is pronounced "Jeff."
My name is Geoffrey and I live in Holland. We pronounce this name in two versions:1) Jeffrey (Djeffrey) 2) Geoffrey (Djoffrey)But in Dutch the pronunciation of Geoffrey is 'Djoffrey' and not 'Djeffrey' (Jeffrey). This is because of the 'o' in the name.For example: the name 'George', is pronounced as 'Djorge' and not as 'Djerge'. So, it's very strange you pronounce Geoffrey and Jeffrey as the same name.But in Holland Jeffrey is more common than Geoffrey, but of course I like my own spelling better.