I currently have two independent TM backups. One started off as the clone of the other. I did it such a way that Time Machine thinks that they are the same TM backup when I plug in either drive, which is not what I intended. This means if I plug in TM Drive A, perform a backup, dismount and unplug it and then plug in TM Drive B, TM tells me the last backup for that drive was time of the last backup I made to TM Drive A. I'm pretty confident I read somewhere that it's possible to have TM recognise each TM Drive as a unique TM backup, and therefore properly report the lapsed time since each backup correctly for either drive. I'm about to upgrade TM Drive B, which will entail cloning it to a new USB 3 HDD. How do I do this and have TM recognise it as a unique TM backup and thus report the correct lapsed time in future?