If it's exactly the same DVD what's wrong with them keeping it available for people to buy? That's not a double dip. All it means is that they wanted to continue selling the DVD, but realized that it's kind of stupid to still have a "20th anniversary edition" DVD on the shelves five years after the 20th anniversary. All they did was change the DVD artwork to fix that. I definitely understand about being angry at unnecessary and greedy DVD double dips, but this definitely isn't one of those. It's just the same DVD still being sold simply so that people can buy it. It also isn't first time that companies have just updated the artwork on DVDs that have already been available for a while, especially if it's simply to remove references to some long past anniversary, and it's also not the first time that a DVD that has already been available for some time was repackaged with some extra stuff (non DVD things I mean) to make a gift set. It's nothing new, and there's nothing wrong with it. A person who just impulsively buys a DVD they already have without checking the features to see that it's exactly the same version that they already have is doing something really stupid, and it's their own fault.
Giving this DVD a lower rating just because there's nothing new on it is pointless. You're basically complaining that the studio ran out of the original supply of a DVD they were selling, and had to make more of them.