How does the Logical System GUID get created

In R3 table CRMPRLS has a logical GUID for its logical system name.  How does this get created/updated?  Is it created during the initial replication of the data between R3 and CRM?   Why I am wondering is my systems where working ok in my QA environment then something happen to change LSGUID in my CRMPRLS table on R3.  So now my middleware is not working.  I will use notes 588701 and 765018 to fix the problem, but I am trying figure out what caused it before it happens again in my production environment.

We are doing one thing to mention is that our R3 environment is being setup to talk to 2 different CRMs.  I am wondering if the setup of the second CRM caused the guid to change.  If so what step during the middleware setup of CRM would cause that?

Thanks.

Matthew