What happens if you mix instant pudding with cook and serve pudding?

Mixing instant pudding with cook-and-serve pudding can lead to an inconsistent texture. The instant pudding will thicken quickly, while the cook-and-serve requires heat and time to set, potentially resulting in a lumpy mixture. The flavors may blend, but the final product may not achieve the desired creaminess or smoothness typical of either pudding type when prepared separately. It's generally best to use one type at a time for optimal results.