I have faced evil, and I have sneered in its cute little face.
Strictly speaking, the PSP version of Lemmings does come with 36 PSP-specific levels, but they have been thoughtful enough to split them off on to their own menu where those of us who want to beat the original game can do so without ever seeing them.
To follow up my earlier rant about Mayhem 23 (“Going up…”), there’s a workaround to the bug. You can have a basher dig – just a little – into one of the walls of the chute and then turn him into a blocker, which does the same thing as the ceiling did in the original level. You can’t put a blocker on the wall of the chute and have him block anything, though, because he’s on an incline and lemmings will just blow by him.