It's not a rip off, but if one listens one can hear the resemblance between
them. In TLK it's strings with lower percussion and in PoNR
it's a Sam Ellis' voice that represents the strings and it has stronger
percussion. But it's easy to forget that Zimmer wrote PoNR before
TLK. Just like it's easy to forget that Basil Poledouris wrote the
powerful theme to Conan the Barbarian (1982) before Jerry Goldsmith
came up with his theme to Total Recall in 1990, which is a complete
rip off.
Compare:
One theme of the K2 soundtrack is the theme of Drop Zone.
Somewhere in the 19th minute of Alabama (Crimson Tide) is a passage that is heard a lot in Broken Arrow. (the end of Mine for example)