I forgot to mention something that happened to me a couple of weeks ago when I redeemed a raincheck for the BOGO Dentastix. The cashier saw that I had coupons attached to the raincheck and called over the customer service manager on duty. As we waited for the manager to walk over, I pointed out that the coupons had not expired, and the cashier said the store has a new rule in place requiring a manager to clear all coupons being used on a raincheck to make sure those coupons were available at the time the raincheck was issued. I would not have been allowed to use any coupons that had only become available after the date of the raincheck.
ETA - I doubt the managers are going to be able to keep track of every coupon out there and when each one first became available (especially manufacturer coupons), so I think the new policy at that store is likely to be focused on preventing double-dipping with Publix store coupons. In other words, they don't want people cashing in a BOGO sale raincheck written on June 10 and also using a Publix coupon for that item that was not available until June 25.
Target, Winn Dixie
True BOGO, No Doubles