Are you sure they are cracked? Some of them have a parting line (usually somewhat invisible) from the factory- if it is visible, somebody probably put them in with the wrong or no toole- If they are very straight lines, that is likely what you are seeing...
Ok, that's not cracked. That's delaminated. No big deal. Just replace the bearings and make sure the cam rotates freely by hand with the new bearings. Those bearings are not new.