Whenever you hit the save button Maglr saves any changes to the publication but it also makes a backup of the publications current state and saves it in case you make some form of an accident where you need to restore a back-up.
Back-ups are useful for when you may have an unreliable system or internet connection, so when one of those factors gives up and you think you've lost everything, you can recover most of your work through the backup function.
Note: Be sure to hit Save often when creating or editing any form of a file! It's better to be safe than sorry when it comes to a dire situation when a system or internet connection gives out.
To Find this option, simply mouse over the options drop-down menu in the top right of the editor. You will see the option called Retrieve Back-up. Click this option and then a window shall appear with the different backups that Maglr has saved.
Select the appropriate backup you wish to recover and then select the Apply button in the bottom right of this window. The publication will then refresh with the state of that backup you had chosen.