I completed hard mode for the black side only but I didn't know it would immediately switch over to the white side. I followed this guide:
It said to start the hard mode on the black side and then start on white side using the normal difficulty. But if I select New, it says it will overwrite the current data. What I'm afraid is is that if I overwrite that data, would I be able to start a new game with the White side and complete a normal playthrough and then level select all the levels under a hard difficulty? Will the black side levels still be available in that stage select mode? Will I be able to obtain the Normal playthrough achievements using the stage select mode for the Black side? Any help would be appreciated.