I use two separate backup drives to backup my iMac and MacBook. I call one drive Time Machine and the other drive Mobile. On Mobile, it shows a folder called Backups.backupdb and inside it has a folder for the iMac and the Macbook. On the Time Machine drive it has the same folder but it is greyed out. When I click on it to try and verify the two folders inside of it, nothing happens. Any thoughts on why this is happening?