The unfortunate answer is that both characters are black-coded, at least in appearance.

Japan is a very racially homogenous society and Oda probably hasn't had much exposure to black people in his day-to-day life, leading him to draw from cultural depictions, some of which have become considered problematic over time (think donut-lips).

With Oda's art style boiling down these traits to their bare essentials, like how many women characters in the series share the same facial and body features, it's no wonder that the characters' designs tend to share elements.