Wish someone could make an plugin that allows merging of notes like you can do with citations. I imported a gedcom with several thousand notes and there are a lot of duplicates. Right now I’m using the isotammi multimerge plugin but it’s real slow going.
I think you want something more akin to the Media merge addon. Where the tool does a checksum comparison of the Media object (or, as you’re requesting, Note object) and automatically merges them if they are the same.