Well, i'm writing a tutorial on what mobius does, so soon there will be more specific.
Yes, they cancel each other.
This is a rather common trick - you use a transform A as pre_transform, and then a transform B that cancels A as post_transform - and then do stuff in between them.
For example: mobius -> something - > mobius inverse
spherical -> something -> spherical
circlize -> something -> squarize
As you apply other transforms between those two, they don't really cancel each other.
For example, look at the example 1 here:
http://tatasz.deviantart.com/journal/Us ... -618952645I used spherical -> preblur -> spherical. Sphericals cancel each other, yes, but putting the pre_blur between them allows me to blur areas that just pre_blur would not blur.