Two Time Machine Backups

I have a time capsule for my time machine backups and a second time machine on an external HDD for my iMac. I understand that they will alternate the backups.
When I open time machine from the dock how can I access that second time machine?

MichaelQ said:

.... I understand that they will alternate the backups.
...

Click to expand...

What do you mean by that? If your understanding is that a single Mac will create a TM backup on drive A at 9:00 and during it's next hourly backup at 10:00 it creates it's backup on drive B, that would not be correct.

TM backs up to the single drive that you have selected for it to backup to.
Opening TM is going to access that single drive which that particular Mac is using to make it's backups.

Hello bobtomay, perhaps you are not aware of this facility because it is fairly recent. See Mountain Lion: Backing Up to Multiple Time Machine Drives - The Mac Observer

However since I went searching for proof of my ability to have more than one time machine I found the answer to my query. See below:-

"Time Machine will show you files from the volume it most recently used for backing up content. If you need to see files from a different backup location, just choose Time Machine > Browse Other Backup Disks.
Your Mac will rotate its backup schedule to include all of the volumes you add to Time Machine, which is great because that means you can easily have separate backups at work and home simply by keeping different hard drives at each location.
It’s also great for automatically backing up to more than one Time Machine volume at the same location. For example, you can backup to a Time Capsule on your own network, and have a second backup on a hard drive connected directly to your Mac — and you can never have too many backups of your important data."

I did not know that - guess I never considered it since I use SD! for bootable backups.

Appreciate the feed back and the article about it. Learn something new every day!