GranPrix

I had a small accident about 10 months ago my left pads were changed with generic ones and kept my Stillen metal matrix ones on the right. Obviously the generic pads wore out already (mind you the stillens are 1 year and 10 months old, still going strong). The generic pads wore on the back side of my Brembo cross/slotted rotor and cut a couple grooves on it. How bad is that and should I change the rotor. I have an extra Brembo rotor but but the direction of the slots and cross holes will be different, can i still use it?