I think that many anti VBAC doctors won't care whether you've had a vaginal birth or not, and some hospitals have an all out VBAC ban.
I do think, in general, it may be easier to find a doctor to support you in a second VBAC, but it definitely isn't a given.
My OB with my VBAC was not super supportive. She was the "whatever you want to do, but are you sure you don't want to schedule that c/s?" type. After I had DS2 though, in the delivery room she said "you should definitely do this again!" It was a very good VBAC