The film should have an emulsion number on it. Similar storage conditions are also important. Film with matching emulsion numbers from two difference places may be slightly different.
The best way to make sure everything is consistent is to buy in batches from a pro photo store. Try Freestyle, B&H, or Ultrafine. Many of the Superia products appear to be gone, so Ultrafine, which buys and cold stores trucks of film to be sold later, may be your best bet for getting Superia Press packs.