Game Progress Lost

You probably did not sign into Game Center on the previous device. That makes your old SW account a Guest account and your progress was not saved via Game Center. Now that you have bound a new level 18 SW account to your Game Center account, you cannot bind your original SW account to the same Game Center account anymore. To check, please go to your previous device, and see if your original SW account is still on the old device. If you really want to save the progress of the original SW account, you would need to create a new Game Center ID and then bind that account to it.