Why has a Daffy Duck episode been replaced with a different episode?

I purchased a box set of cartoons in 2014 featuring Daffy Duck in order to have an episode titled "Duck Dodgers IN the 24 ½th Century". I was surprised recently to see that it has now been replaced by "Duck Dodgers AND THE RETURN OF the 24 ½th Century" - a later cartoon.

The description for the cartoon I now see still contains the description of the original cartoon, which of course does not match what it shown when the replacement is played.

Any ideas why the original has been replaced??

It's one of my two most favourite Daffy Duck cartoons!