Do a nandroid before any major changes, just in case that change doesn't work. You can make as many backups as you like, and I suggest copying them to your computer and renaming them to something you'll understand. Then, should you need to do a backup, just copy the one you want back over to your card and do it from the recovery console
Or, just leave them on your card if you've got the space, and select the one you want. It'll give you options of which one to use. I still suggest renaming them for ease of selection