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true, but in this case, you already have 2 blades for the frameback.
You can only replace them with the exact same shape. It's literally more of the same.
Unless you want say 7 ideantical blades...

I suspect any custom blade maker could do this. The lack of geometry would make this a fairly trivial task.
It won't be cheap though. Because the blade needs to be fitted precisely to the frame....