I have a backup up of several computers mounted on my computer. I frequently (but inconsistently) get duplicate suggestions in the 'open with' drop down menu. When the system searches for useable apps with regards to a filetype, it seems to search all connected disks. If I select the wrong one, I have to wait for my backup drive to spin up for the program to launch. Does anyone know of a way to keep copies of an app from showing up on the list, short of keeping the backup unmounted?