How is this better than the already existing mod https://mods.factorio.com/mods/mickael9/cut-and-paste ?

Interesting, I've not seen that mod! This mod is simpler (less configuration, and now support for tiles etc).

The main benefit that this brings over the other is that when you cut the items are immediately flagged for destruction allowing the destination paste location to overlap with the source from where the items were copied.

I've been using instant blueprints (creative mode mod) and at least with that cheat it's possible to cut and paste overlapping sections.