When a user gets an enrollment invitation (self-signup or invite) that uses an OIS in the process, a non-mutable OrgIdentity record is created in the process.
If the first petition is denied, cancelled or not completed and a new petition is started (by clicking on the original link), the new petition does not allow linking the OIS data. The datamodel links the original OIS record to the first petition and throws an exception if such a record was already found.
The use case is the situation where a user receives a link to the wrong petition first. He/she starts the petition, but the administrator realises the user is to be enrolled in, for example, the wrong COU. The administrator then sends out a link to the correct petition and requests the user to enroll using that link. This second petition will then fail with an ugly 'Invalid Token' message.