That also crossed my mind and seems plausible. The thing is, and I know it's just a character name, but the
Linda Carter character has a direct connection to Avengers while I couldn't find a direct connection with
Christine (included a link to their wikia pages).
I feel like, if Rachel was cast as Linda Carter there would have been more opportunity to expand her role in the Marvel universe, because she has a presence in the Comic universe. Linda even has her own Night Nurse series. Linda makes appearances in Spider-Man, Luke Cage, Captain America/Civil War and Doctor Strange (to name a few) which are all part of the current Marvel universe. You would think it makes more sense for Rachel to be Linda, so she can have cameo/appearances in the current Marvel movies and series.
Maybe they just changed their names, or maybe Christine is going to be different from the Comics. I just hope Rachel has a good arc in the movie, and not "just" the girlfriend/ex-girlfriend/damsel in distress