You know if you go to the One Piece Wiki and look up Degrossa, or however you spell it, there is headshots of all the people associated with the place and the headshots of both are just one or two spots below/above each other. They look to similar not to be the same person unless they're sisters. But until Oda gets better we won't know for sure. So here's hoping for a quick recovery.
I'd go with them being sisters. While they do look pretty similar, Baby 5 has longer hair, curlier hair (it almost looks like Perona's), and has different bangs. Personality wise, they're both pretty passionate and rash, but Baby 5 is more vocal about her need to be 'wanted' while Violet just seems to be the 'in love with the idea of love' type.