No, the DVC resorts do not have/offercots or rollaway beds. The beds in the unit are what you get. Configurations of the second bedroom vary, but all Master bedrooms have a king bed and all the living rooms have a queen size sleep sofa. The second bedrooms have either two queen beds, a queen bed & a queen sleep sofa (BCV only), or a queen bed & a double sleep sofa.
If you have a need for more beds and aren't exceeding the maximum occupancy for the unit, consider bringing along an aero bed. Some members do this for their children who can't or won't share a bed.
Another thread mentions that some of the DVC resorts have aerobeds to use for free. I don't think they can be reserved, however. It might be worth a call to the front desk of whichever resort you are considering, especially if you are arriving by plane (those aerobeds are heavy!)