If you go from semi metallic to sintered you can use the same rotors but I would advise cleaning the rotors first to remove the previous pad material. To do that just use wet and dry ( dry) on the pad contact area both sides. Rub across not along the rotor rim. Then clean with brake cleaner or IPA and leave for 10 minutes to allow the brake cleaner/IPA to fully evaporate. Then you are good to go with new sintered pads which will of course need proper bedding in.