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How do our favorite duo figure this out? Do they? Or is it Jimmy Olsen, Perry White, or even Cat Grant ...

At first, I thought that this sentence was going to end with, "...who is the secret agent?" shock

Of course, since all of them worked at the Planet even prior to Superman's first appearance, we would have one of two possibilities:

1) An alternate universe with an alternate timeline for hirings.

2) The Bureau 39 person was planted in the Planet purely for intelligence gathering: so that they would have access to national and world news as it happens.

Joy,
Lynn