Each reseller account, customer account, and subscription has an additional property, Globally Unique Identifier (GUID). The GUID is assigned by the server when an object is created. It does not change during the object lifetime (unless there is a special request to do that). Thus, the object can be identified by GUID even if its ID in Plesk database was changed while restoring Plesk data or migrating the data from the other server. The operations on GUIDs are available in XML API 188.8.131.52 and later versions.
In some cases, the object GUID needs to be changed. For instance, two different objects on different Plesk servers might have the same GUID. When merging data from the servers, such collision is resolved manually by using a special XML API operation that generates a new GUID for one of the objects. There is no way to assign a specific GUID to an object. GUIDs can be changed by the Administrator only.
Plesk user accounts are restored from a backup with the original name and GUID. For instance, there is an account named MyObject1 with GUID1. If it is backed up and then is renamed, or its GUID is changed, the object will be restored as MyObject1 with GUID1 from the backup.