Maybe Nicky put Cassangelique on a budget and she had to borrow a few things that the Phoenix left behind.
I remember having an outfit back then where you could add/remove collars, hike the dress up/down, add a belt or not. You got more mileage out of clothes back then; everyone thought you had an extensive wardrobe by what you added or didn't.
Anyway, Cassangelique was just following what the royals do--reuse, reuse, reuse--or maybe Ohrbach's had a limited line of clothes.