TLDR: Why the fuck is a senior developer creating multiple instances of a core piece of logic all over the fucking application?!?!?!?

Context: I am also a senior dev, and have worked with this guy for years. He has even completed me on my clean code practices and architecture, so I really cant understand why he would copy and paste a public class into 3 other models on the project instead of just referencing the original. I’m just posting this hear as my version of screaming into a pillow in frustration, and to avoid badmouthing him to co-workers.