I, too, have duplicates though not in medium format. I came to conclusion that I like gears. I like using different gears. I like how each one is different. Do I need all that duplicate to take great photos? Perhaps not. Do I enjoy using different gear as part of image making process? Yes.
I think, there is a point in future, things can get out of control and have simply too many. I think, that point is, when I forget I had a certain camera. I'm not even close to that.
I realize, this is my hobby. As such, I enjoy it the way I see it fit.
I don't know if I am really answering your question but I think, the only person who can really answer it is yourself....