Frodo’s other friend

[Zigûr]

I've noticed Folco too! I think he's a great example of the way Professor Tolkien adds more depth to his world. It's not just in terms of references to The Silmarillion and events of ancient history; we get observable indications that, for instance, Frodo's circle of friends extends further than just the main hobbits of the story.
Given the confusion over which hobbit went with what name and so on in the drafting of the early chapters I'm not surprised there's a character who shows up and disappears again. That being said I think it enhances the realism somewhat; was Folco even in on the plan? Perhaps not.