Mike Dailly mentioned in an interview that there were hundreds of levels that didn't make the cut. To the best of my knowledge, only two such levels (three including this one) have been seen publicly in any form - "One Way To Freedom" was included in a demo version, and "The Sky At Night" was shown on-screen in said interview (but has never been playable to the public). It's also plausible that some of the unique / replacement levels in versions released around the same time as Amiga (eg. Amiga budget / bookclub versions, Mac's alternate Tricky 21) could be from the cut levels, but we'll likely never know for sure - it's equally possible they were made on-demand.

The history is fascinating.  Is anything known about the following?

a. Was the original Amiga level editor ported to other platforms, or were were the official levels all created on the Amiga?  The youtube video shows that the Amiga editor uses the hardware to show high resolution text under the main low resolution game area, which would not have been possible on a contemporary PC.  I have also noticed that the palettes of the "special" levels in the PC-exclusive Companion and Covox sets have all their RGB levels rounded to a multiple of 4, indicating that they were created on an OCS Amiga (which only had 4 bit RGB resolution, rather than the 6 bits available in VGA).
 
b. Were the unique Genesis levels designed by DMA, or were they outsourced?  Same question for the Companion book and Covox levels.