Yep, another great reason for you to end this T- I don't mean her treating your friend differently but you two having the same T. I think it's best not to share T with s.o. you know and if this can't be helped talking about it is not that helpful.
Going 40 min over regularly sounds unprofessional- but yet again your T wasn't that great with boundaries even with you so why expect her to stick to them with other clients?

More generally, I believe every T-client RS is unique- every client needs T to treat them a bit differently. My T "shares" my dark humour- is he joking with others? Guess, no. Some clients would be offended. Is he doing this just to help me out? Probably.
All and all I believe Ts react differently to each client- hopefully providing them with the best possible therapy for them.

BTW, I love Hope-full's Fair is not always equal and equal is not always fair.