I searched Walgreen's coupon policy and couldn't find anywhere that stated they don't accept manufacturer's with references to other stores on them so it will be up to your store whether they accept them or not.
The coupon prints with “available at Walmart” but with no logo.
Diet Pepsi 2-liters .99 thru 2/2
Use .50/1 Diet Pepsi 2-liter or 7.5-oz. 8-pk – search under beverages
Final price: .49!