If an object enters the battlefield as a copy of Catch of the Day, it copies the values chosen previously for Catch of the Day’s enters-the-battlefield replacement effect. However, as the copy enters, it’ll also apply Catch of the Day’s replacement effect again, allowing the copy’s controller to choose an option for Keyword, Whenever this creature attacks, and Size. The newly chosen Size will overwrite the original Catch of the Day’s power and toughness, but the newly chosen Keyword and Whenever this creature attacks abilities will be added on top of any copied abilities. For example, this can cause you to have a Catch of the Day with vigilance, ward {3}, and two “Whenever this creature attacks” abilities. You can even make the exact same ability choices as the original Catch of the Day, and the copy will have two instances of the chosen abilities. For instance, you can have a creature with ward {3} and ward {3} and “Whenever this creature attacks, scry 2” and “Whenever this creature attacks, scry 2.” Each of those abilities would trigger separately.