What are they called?
Have you tried mounting one of the images to see what's in it?
I wonder if your external is getting lost & TM is using this method???
In Finder's Menu, select Go menu>Go to Folder, and go to "/volumes". (no quotes)
Volumes is where an alias to your hard drive ("/" at boot) is placed at startup, and where all the "mount points" for auxiliary drives are created for you to access them. This folder is normally hidden from view.
Drives with an extra 1 on the end have a side-effect of mounting a drive with the same name as the system already think exists. Try trashing the duplicates with a 1 or 2 if there are no real files in them, and reboot.
If it does contain data...
http://support.apple.com/kb/TS2474