The two phases are very similar in meaning. The words "gates" and "doors" refer to the gates of the temple. The writer is speaking to the gates as if they were a person. A gatekeeper would be the one to open the gates. Alternate translation: "Open up, you ancient gates" or "Open these ancient gates" (See: [[rc://en/ta/man/jit/figs-parallelism]] and [[rc://en/ta/man/jit/figs-personification]])