Hybrid Cavalier does not have a "Hybrid At-will 1" selection. Instead, when you choose their Hybrid Virtue, it gives the at-will associated to that Virtue, and adds a "Virtue of [X] (Hybrid)" entry to the powers page. Once they have selected a power from their other class in the "Hybrid At-will 1" entry, they can then select any power from either class in the "Virtue of [X] (Hybrid)" field, which can include paladin powers or the powers from the other class. This allows them to have two at-wills from their other class at the same time, which is not a legal hybrid build.
Hybrid Cavalier does not have a "Hybrid At-will 1" selection. Instead, when you choose their Hybrid Virtue, it gives the at-will associated to that Virtue, and adds a "Virtue of [X] (Hybrid)" entry to the powers page. Once they have selected a power from their other class in the "Hybrid At-will 1" entry, they can then select any power from either class in the "Virtue of [X] (Hybrid)" field, which can include paladin powers or the powers from the other class. This allows them to have two at-wills from their other class at the same time, which is not a legal hybrid build.