Question on 'cast' and 'typeof'

In some of the SAIL recipes, I sometimes see a construct like:

union(local!datasubset.data.x, cast(typeof(local!datasubset.data.x),{}))

I'm not sure why 'cast' and 'typeof' are used in this case. In all of the use cases I've run , I get the same results if I do:

union(local!datasubset.data.x, local!datasubset.data.x) to get 'distinct' values

Am I wrong? Missing something important?

OriginalPostID-195870

OriginalPostID-195870