Miami Dolphins only came into being in the early 1960s. I think Redcliffe calling themselves Dolphins pre-dates Miami.
That aside, it is one thing that irks me about the NRL, using too many NFL names. Raiders, Steelers, don't forget those. I actually wish more sports and teams adopted ye olde names instead. NFL had a lot of weird ones like Triangles, Yellow Jackets, etc. AFL with names like Shinboners, Same Olds. RL names like Shoremen, etc
I long for weird ye olde names.
Oh, and the GC did want to use Dolphins not Titans but Redcliffe blocked them. And it paid off, they will have their own team in the NRL now