I also agree that with 2 kids, it's fine. We thought about it when #2 was born, the name I really liked also started with a D, in the end we went with something else. But I couldn't see doing it for all 4 kids, being limited to only names that start with one letter. Mine all ended up with different first letters, but I still like that name we didn't use for #2, so if we have another boy, the first and 5th will both start with D.
and yeah, I totally thought of the Duggars!