For a moment Antoinette looked very much like Amélie. Perhaps they are related, I thought. It's possible, it's even probably in this damned place. (II.6.3.10)
Here, Rochester is so convinced of Antoinette's status as racially inferior to him that everything he sees confirms what he already believes. Like the scene with Amélie's "intimate" gaze, Rochester reads a physical similarity between Amélie and Antoinette that justifies his treatment of them. That he can have sex with them without calling it "love" is supported by the fact that both relationships involve financial transactions: he gives money to Amélie, but receives money (as dowry) from Antoinette. No wonder Amélie says that she will try to feel sympathy for Antoinette – you could say Antoinette gets the short end of the stick.