WD Smartware keep the data of each PC separated, when you are restoring data, you will be presented with the option to choose the backup that you will restore.
Example:
PC1 backup
PC2 backup
PC3 backup
Computer number 3 crash and you need to do a restore, you just start the restore process and you will be able to select what backup to restore.
Or, as pizza stated, you can manually copy the data from the drive to your new computer.
