The reason for the problem is that the GUID is the same as an existing site. You could either delete the old site or create a new web application andin that new one.
And in the microsoft.com , it said:
To back up and toprofile information, you must perform the following actions:
- In Office SharePoint Server 2007, you must complete a full SSP and restore operation. For example, if you are concerned about data corruption in the SSP database, and you have a from before the point of suspected corruption, you can restore that SSP to obtain the full set of information.
- In SharePoint Portal Server 2003, you must complete a full backup and restore operation for the _PROF database that the portal application uses. This process may require that you restore the portal application.
The following are the two components to the My Site data:
- Personal site – The personal site includes documents and lists. This information is stored as a SharePoint site in the content database.
- User profile – The user profile includes information about profiles, links, and details. This information is stored in the SSP or in the_PROF database.
If you want to restore user profile data, do not create a new SSP. There is no supported way to back up only the profile information from the SSP, and then to restore the information to a new SSP.