A1Click is not a registry cleaner. It is a drive cleaner. A1Click does have a minimal registry cleaner in it for removing tracks, but A1Click mainly cleans junk files from the hard drive. RegVac does not clean the drive. RegVac cleans the registry. So RegVac does one thing and A1Click does another.
If you purchase RegVac, you should still use A1Click but I would suggest that you uncheck the Registry Cleaner part of it.