You probably will want to post this over on the Disney Resorts forum for more responses. But, I happen to know that Disney will transport your luggage from one hotel to the other; however, you would probably be happier to just take a taxi with your luggage as you go from the Poly to OKW. Even if you have to store your luggage at Bell Services, you will know that it made it.
I've heard one too many stories of lost bags to want to risk Disney handling my bags on a split stay.
Have a great trip!
disneyaogoo