Qt5+Python3, grid, deduplicator concept: how?

Question

Python

I'm designing the user interface for my desktop program. Rested on how best to make a deduplicator. The fact is that one of the columns of the table (grid) contains values ​​that can be the same, and they must somehow be marked to group or possibly exclude such repetitions. These values ​​can be very similar, and then they must be caught manually. Obviously a many-to-many relationship. It must be done according to the mind, and for example CRUD is not suitable here. Table rows can be ticked.
The buttons that came to my mind are: find everything by label, new label, update in the database, remove the label, and, accordingly, the traditional OK and Cancel to save or cancel changes.
What editor buttons would you provide if you were me, to put things in order in the data within my table? Maybe you need to store the IDs or hashes of the fields that are duplicated in a separate service table and make links to it from the main table to be edited?
If there is a theory in mind, I will be grateful for the indication of the source, which should be read.