duplication
noun [ U ]
uk/ˌdjuːplɪˈkeɪʃən/ usthe practice of doing the same thing more than once, or having more than one person or thing to do the same task, when this is not necessary:
As a result of the merger, there could be duplication among the two companies' administrative staffs.
There was enormous duplication of effort with each area having its own personnel team.
duplication of functions/roles/services
avoid/eliminate/reduce duplication
the practice of making an exact copy of something, especially when this is illegal:
The defendants never denied the illegal duplication, but claimed they had tried to obtain copyrights.