I can't imagine I'm the first person to have noticed this, but it's worth pointing out regardless. The bits I've italicized from the first scene, along with the whole idea of the exchange, seem to have served as writing prompts for Shakespeare in King Lear. Translation: He recycled his own stuff, assuming no one would ever notice. What's exciting for me is that the second passage is so much more sophisticated than the first. Edmund wants his father to notice the letter and make him hand it over; the word "nothing" is an important thematic touchstone in King Lear; unlike the earlier play, King Lear alternates between verse and prose for effect, and here shifts into prose for a sense of intimacy that contrasts with the earlier, formal verse of the play's first scene. Shakespeare learned a lot in the years between these two passages.
There are dozens of these self-plagiarisms -- I call them echo scenes -- in Shakespeare. As the mood strikes me, I'll post more.