you can select the vector and hit the n key to start node editing mode, you can smooth out portions and it has little handles, youll see
but its not gonna give you perfect lines the way you want ever, you have to put in the work, trust me
the only thing i can think of for why it creates a copy when you move the ellipse is when you hold crtl and move, but if your not holding crtl key then i dont know about that one