Mylio is designed to run as a single instance of your library on each machine, this means there can not be multiple Mylio libraries within the same user on a single machine.
If you would like to run multiple copies of Mylio on the same machine, you can do so by utilizing separate users. Each user will count as a device towards your device limit and take up the space needed to store your images, possibly duplicating the space needed to house your photos. Additionally, since Mylio uses peer-to-peer syncing, you will need at least one additional device set up as a Mylio account to populate the second user. Generally, it is best practice to use an external hard drive as a secondary device that can hold your originals when switching between users.
Below are links to support material from Apple and Microsoft for setting up new users on different operating systems: