I'm not good at faces, especially in still photos, but from the costume, I'd put the first picture of Lucy Tonge as early 1860s, and the second one as early to mid 1880s, which could support the "same person many years apart" hypothesis. This is, however, going from dimly remembered knowledge of Victorian costume history and family photo-dating from many years ago, so could be wrong. If I remember it correctly, if you can see a woman's ears, it's after 1865.

And Googling Maull and Polyblank, who took her first photo, reveals that the company only existed until 1865, so there's confirmation of the dating there.