Hi ulisses, the standard CAD fillet (called "rolling ball fillets") keeps a uniform radius value and lets the width of the fillet change to a longer or shorter arc.
So for example in the case you show, if you make a fillet of radius 0.6, you should see that both of these edges are radius 0.6 arcs:
Some more details and illustrations of the constant radius fillet behavior here:
In the fillet command there is a "Shape" option that you can switch from "Shape: Circular" (which makes rolling ball fillets) to "Shape: Const dist" which will allow the radius to vary and instead keep the distance between the arc's endpoints to be a constant distance, try setting that:
When that is in place, the 2 edges shown above will be arcs of different radius values but the chord length between their ends will be constant:
ulisses_fillet1.jpg