If you plug a normal map into the randomizer - the randomizer knows that this is a normal map and it should be treated in a special way (if you rotate a convex thing - it will remain convex)
if you plug a bitmap into the randomizer and then into a normal node - then Corona will take the result of the randomization (the normal map rotated and transformed the way you set it) and will then interpret this as a regular normal map - so whatever is red will be treated as red, whatever is green - as green, and whatever is blue - as blue) - this can result in "flipped normals" effect
the different orders of bitmap > normal > randomizer > triplanar will produce different effects - you may sometimes want to use the "incorrect" order if it makes sense in your specific case