Were they created by the same person?
Hmm… not sure what you’re getting at there, smithy, but I would certainly say yes. Not only do they appear to have been written by the same hand in the same meticulously neat format but they were both included in authenticated Zodiac letters where there is very little doubt on the handwriting.
Also, this…
viewtopic.php?f=81&t=821
E., well, the 340 was in with a card (probably!) but that apart, I was just wondering if we generally think that yes, they were drawn up by the same person.
That’s all!
Yup, same person.
“I don’t know Chief, he’s very smart or very dumb.“
Yes. I too think the same person, but I admit smithy…you made me look. 
I think there are things a copycat would overlook. I wonder if a copycat would notice things like the forward 3-stroke "K", but the simpler 2-stroke reversed "K"…if the reversed "K" is meant to be a k. Probably.
“…they may be dealing with one or more ersatz Zodiacs–other psychotics eager to get into the act, or perhaps even other murderers eager to lay their crimes at the real Zodiac’s doorstep.“ L.A. Times, 1969
Indeed! 
Is there anything that indicates they might not have been produced by the same person?
Indeed!
Is there anything that indicates they might not have been produced by the same person?
No.
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I don’t believe in monsters.
No, there isn’t, is there.
I’m quite prepared to believe, myself, that they were concocted by the same individual.
Thanks! As you were!
