I don't think this would be very hard in Orlando if you were at one of the bigger resorts, as long as you didn't include the most popular times. What month did you have in mind?
I've only stayed two weeks in a row, but the resort was very happy to rearrange our reservations to keep us in the same unit for both weeks. Some of the resorts are more customer friendly than others.
Off the top of my head, Mystic Dunes, Vistana, Summer Bay and HGVC would probably do this with no problem. OLCC, maybe not.
The best time to do this would be when you could catch a bulk banking. I know HGVC just had one that included next Fall. If you're a TUG member, watch for the bankings there.
Sheila