I used to backup my old Mac Mini (OSX Tiger) on a partition of an external harddrive a few years ago. The backup was a bootable backup, in short a near perfect copy of my working system (Tiger). I recently got a new Mac Mini (OSX Mountain Lion) and plugged in the old external harddrive. Which was fine. However I've noticed that if I right-click on a file then applications from both Application/ folders are being picked up. i.e. I had Smultron and Komodo Edit on my old Mac Mini (now on the external HDD partition), and my current Mac is picking this up as well as my current /Applications on my internal HDD. How do I stop it from picking up these old applications? It is neat that OSX does this in some ways, however I don't want multiple choices of certain apps, or old apps I no longer use being picked up. Note that I still want to keep that bootable backup so deleting the old Application/ folder is not an acceptable workaround for me. Thanks for any input!