The MyPet storage is way to have more than one MyPet.
This doesn't mean you can have more than one pet active at a time but to store any pets you don't want active at the moment.
The amount of pets a player can store is limited by the following permission:
Xneeds to be replaced by the amount of pets a player should be able to store.
Xneeds to be smaller or equal than the
MyPet.Max-Stored-Pet-Countin the config.
Because the server needs to check a lot of permissions in order to check if the player is allowed to store more than his currently stored pets, this config setting jumps in and limits these checks.