I have noticed this bug on many computers where I have installed both Comodo firewall & CCleaner. On Windows' own application manager, Comodo is only appearing once. It's also appearing once in Advanced Uninstaller PRO, so that's why I think that's a bug in CCleaner.
Possibly the way the uninstaller information is stored in the registry since that's where CCleaner is getting the uninstall list from - if that's the only uninstaller you're seeing this happen with. One thing is don't mess with that duplicate entry, since deleting it or renaming it may actually break the ability to uninstall the program.