.Mac: Backup "You have already backed up another Macintosh using this .Mac account..." Alert

Backup is intended to back up files from one computer to one iDisk at a time. If you try to back up two computers to one iDisk, the alert described in this document appears.
Symptom

The an alert box with this message appears:

Solution

Backup is intended to back up files from one computer to one iDisk at a time. To back up more than one computer at a time, use one of the following solutions:

Warning: If you have the same user short name on more than one computer, this alert message will not appear. However, even if it does not, you must not attempt to back up multiple computers to the same iDisk. This may result in unpredictable behavior, including either undesired overwriting of previously stored data or failure (without warning) to save the new data.

Related Documents
86101 .Mac: CD-R / DVD-R Drive Compatibility with Backup
106824 Mac OS X: How to Change User Short Name

Published Date: Oct 10, 2016