Well, ALL the jokes are not. If you'd like we can post both scripts side-by-side for you to compare.
Actually that would be cool to see for a kind of behind the scenes type of thing...
From the way I understand it, they went through each script and depending on the material either threw sections out completely or revamped jokes. Which is why I was saying not "all" the jokes are the same
According to Conor, NOTLD and Carnival of Souls (coming soon) are essentially brand new, whereas Reefer was closer to 80% new material, but HoHH is closer to its original script than the others. The amount of new material varies on each one - some of the ones we have coming up are complete rewrites, but since HoHH was a more recent Legend release, it's closer to the riffing style than NOTLD (with the "zombie recipes" etc).
I also know that they spent almost as much time reworking these as they usually devote towards writing a new riff, so it's not like they just went through each line and replacing words. I'm certain they took each joke into consideration.